1 ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 86 RIN 2060 AK76 Emission Durability Procedures for New Light Duty Vehicles,

Light Duty Trucks and Heavy Duty Vehicles AGENCY: Environmental Protection Agency.

ACTION: Notice of Proposed Rulemaking.

SUMMARY: This proposed rulemaking contains procedures to be used by manufacturers of light duty vehicles, light duty trucks, and some heavy duty vehicles to demonstrate, for purposes of emission certification, that new motor vehicles will comply with EPA emission standards throughout their useful lives. Today's action proposes procedures to be used by manufacturers to demonstrate the expected rate of deterioration of the emission levels of their vehicles.

DATES: Written comments on this NPRM must be submitted on or before [ insert date 30 days after Public Hearing date].

A public hearing will be held on [ insert date 15 days after publication in the Federal Register]. Requests to present oral testimony must be received on or before [ Insert date 5 2 days prior to the date of the public hearing]. If EPA receives no requests to present oral testimony by this date,

the hearing will be canceled.

ADDRESSES: Comments: Comments may be submitted by mail to:

Air Docket, Environmental Protection Agency, Mailcode:

6102T, 1200 Pennsylvania Ave., NW, Washington, DC, 20460,

Attention Docket ID No. OAR 2002 0079. Comments may also be submitted electronically, by facsimile, or through hand delivery/ courier. For more information submitting comments and on the comment procedure and public hearings, follow the detailed instructions as provided in Section V, " Public Participation" section. We must receive them by the date indicated under DATES above. Paper copies of written comments ( in duplicate if possible) should also be sent to the general contact person listed below.

FOR FURTHER INFORMATION CONTACT:

General Contact: Linda Hormes, Vehicle Programs and Compliance Division, US EPA, 2000 Traverwood, Ann Arbor Michigan 48105, telephone ( 734) 214 4502, E mail:

hormes. linda@ epa. gov.

Technical Contact: Eldert Bontekoe, Vehicle Programs and Compliance Division, US EPA, 2000 Traverwood, Ann Arbor,

Michigan, 48105, telephone: ( 734) 214 4442, E mail:

bontekoe. eldert@ epa. gov. 3 SUPPLEMENTARY INFORMATION:

I. Background A. Overview of certification process, CAP 2000 history B. Durability demonstration process history 1. Durability demonstration methods used prior to the CAP 2000 regulations 2. Emission durability procedures under CAP 2000 C. Ethyl petition to reconsider CAP 2000 rules D. Judicial review of the CAP 2000 rules II. How did EPA develop the proposed durability procedures?

A. What is the purpose of the durability program?

B. What are the factors that affect exhaust emission deterioration?

C. The strawman durability procedures 1. The whole vehicle aging procedures 2. The bench aging procedures 3. Allowable customization of the bench aging procedures D. Development of today's proposal from the strawman durability procedures 1. The durability objective 2. Cycle severity for the SRC ( Comments 1 and 2)

3. Alternative and customized cycles ( Comment 3)

4. The standard bench cycle ( Comment 4)

5. Bench aging time ( Comment 5) 4 6. Bench aging specifications ( Comment 6)

7. Adjusting durability procedures based on IUVP data ( Comments 7 and 8)

8. Reproducibility by outside parties ( Comment 9)

9. Confidentiality of emissions test results submitted under the durability program E. Diesel Vehicle Exhaust Deterioration F. Evaporative and refueling durability procedures III. What is EPA proposing today?

A. Standard whole vehicle exhaust durability procedure B. Standard bench aging exhaust durability procedure 1. The Standard Bench Cycle ( SBC)

2. The Bench Aging Time ( BAT) calculation 3. The effective reference temperature for the SBC C. Customization of the standard procedures 1. Customization of the Standard Road Cycle 2. Customization of the standard bench procedures 3. Replication by outside parties D. Using In Use Verification Program ( IUVP) data to improve durability predictions E. Evaporative and refueling durability F. Effective date and carryover of existing 5 durability data 1. Effective Date 2. Carrying over durability data G. Miscellaneous regulatory amendments and corrections IV. What are the economic and environmental impacts?

A. Economic impacts 1. Comparison to CAP 2000 economic impacts 2. Economic impact of today's proposal B. Environmental impacts V. What are the opportunities for public participation?

A. Copies of This Proposal and Other Related Information B. Submitting Comments on This Proposal C. Areas where EPA specifically requests public comment D. Public hearing VI. What are the Statutory and Executive Order Reviews for this Proposed Rule?

A. Executive Order 128866: Regulatory Planning and Review B. Paperwork Reduction Act C. Regulatory Flexibility Act D. Unfunded Mandates Reform Act E. Executive Order 13132 ( Federalism)

F. Executive Order 13175: Consultation and 6 Coordination with Indian Tribal Governments G. Executive Order 13045: Children's Health Protection H. Executive Order 13211: Actions that Significantly Affect Energy Supply, Distribution, or Use I. National Technology Transfer Advancement Act I. Background B. Overview of certification process, CAP 2000 history Before a manufacturer may introduce a new motor vehicle into commerce, the manufacturer must obtain an EPA certificate of conformity indicating compliance with all applicable emission standards over the vehicle's useful life period. The useful life for cars and light trucks is currently 100,000 miles or 10 years, whichever occurs first;

for heavy light trucks, medium duty passenger vehicles ( MDPV) and complete heavy duty vehicles the useful life period is 120,000 miles or 11 years, whichever occurs first.

[ Section 202( d) of the Clean Air Act and 40 CFR 86.1805 04]

To receive a certificate, the manufacturer submits an application to EPA containing various information specified in the regulations, including emissions test data. EPA reviews the submitted information as well as any other relevant information, and issues a Certificate upon a determination that the manufacturer has demonstrated that its new motor vehicle will meet the requirements of the Clean Air Act ( Act) and the regulations. [ 40 CFR 86.1848 01] 1 Separate certification regulations exist for heavy duty highway vehicles and engines, which refer to the light duty certification procedures. Today's proposal will apply to those subsets of heavy duty vehicles which use the same certification procedures as light duty trucks. For convenience, the term " vehicle" or " motor vehicle" will be used in this preamble to mean those light duty and heavy duty motor vehicles subject to the proposed regulations.

2 63 FR 39654 ( July 23, 1998).

7 A certificate of conformity is effective for only one model year, therefore, new vehicle certification must occur annually.

EPA's regulations detail the process motor vehicle manufacturers must follow to obtain EPA emissions certification. In 2000, EPA issued a comprehensive update to the certification regulations for light duty vehicles and light duty trucks1. These certification regulations are known as " CAP 2000" ( Compliance Assurance Program) 2. They include detailed procedures on the selection of vehicles for testing and testing procedure, specifications on the information that must be submitted to EPA, and other requirements pertaining to reporting and testing.

Issuance of a certificate is based on a determination by EPA that the vehicles at issue will conform with the applicable emissions standards. Compliance with the emissions standards requires that the vehicles meet the standards for the specified useful life period. A determination of compliance, therefore, must be based on an evaluation of both the performance of the vehicles'

emissions control system when new, as well as performance 3 Since a certificate must be issued before the new vehicles may be introduced into commerce, the emissions testing and other relevant data and information used to support an application for a certificate are usually developed on pre production prototypes.

4 The durability demonstration program consists of two elements: emission deterioration and component durability. Emission deterioration prediction is a process of predicting to what degree emissions will increase during the vehicles useful life. The deterioration factor ( DF) is a measure of the deterioration. Component durability is a demonstration that the emission control components will not break and will continue to operate as described in the Application for Certification during the minimum maintenance interval proscribed in 40 CFR 1834 01. The component durability demonstration is conducted by the manufacturer using good engineering judgement.

8 over the entire time period of the vehicles' useful life. 3 The process of predicting how and to what degree a vehicle's emission levels will change over its useful life period [ emissions deterioration] as well as the robustness of the vehicle's emission related components [ component durability] is known as an emission durability demonstration4. Today's action specifies the methods that manufacturers must use to determine emissions deterioration for the purpose of certification. EPA is not proposing to change the existing regulations for determining emissionsrelated component durability.

Over the years, EPA has promulgated regulations prescribing several different emissions durability demonstration methods to fulfill EPA's need to determine compliance with emission standards over the vehicle's full useful life. The following is a short summary of this prior regulatory history, to put today's proposal in context.

B. Durability demonstration process history 3. Durability demonstration methods used prior to the CAP 5 At the time this durability procedure was effective, the useful life mileage for light duty vehicles was 100,000 miles. Refer to 40 CFR 86.1805 04 for current useful life mileage values.

6 A multiplicative DF is calculated by performing a least squares regression of the emission versus mileage data for each exhaust emission constituent and dividing the emission level at full useful life ( historically, 100,000 miles) by the emission level at the 4,000 mile point.

9 2000 regulations Prior to CAP 2000, EPA's regulations ( ref. 40 CFR Part 86) specified the method to demonstrate a vehicle's emission durability. The method used a whole vehicle mileage accumulation cycle, commonly referred to as the Approved Mileage Accumulation ( AMA) cycle. It required manufacturers to accumulate mileage on a pre production vehicle, known as a durability data vehicle ( DDV), by driving it over the prescribed AMA driving cycle for the full useful life mileage5. This was to simulate the real world aging of the vehicle's emissions control systems over the useful life.

The DDV was tested in a laboratory for emissions at periodic intervals during AMA mileage accumulation, and a linear regression of the test data was performed to calculate a multiplicative deterioration factor ( DF) for each exhaust constituent. Then, low mileage vehicles more representative of those intended to go into production ( referred to as " emission data vehicles," or EDVs) were emission tested. The emission results from these tests were multiplied by the DFs6 to project the emissions levels at full useful life ( referred to as the " certification 7 Reference: 63 FR 39653, 39659 ( July 23, 1998) ( CAP 2000 NPRM).

10 levels"). The certification levels had to be at or below the applicable emission standards in order to obtain a certificate of conformity.

EPA was concerned about the ability of any fixed cycle  including the AMA cycle  to produce emission durability data that accurately predicted in use deterioration for all vehicles. EPA had particular concerns that the AMA did not represent current driving patterns and did not appropriately age current design vehicles. In addition, manufacturers have long identified the durability process based on mileage accumulation using the AMA cycle as very costly and requiring extensive lead time for completion. As a result,

EPA came to believe that the AMA had become outdated7.

The AMA cycle was developed before vehicles were equipped with catalytic converters. It contains a substantial portion of low speed driving, designed to address concerns about engine deposits. While engine deposits were a major source of emissions deterioration in pre catalyst vehicles, the advent of catalytic converters,

better fuel control, and the use of unleaded fuel shifted the causes of deterioration from low speed driving to driving modes which include higher speed/ load regimes that cause elevated catalyst temperatures. The AMA driving cycle does not adequately focus on these higher catalyst 8 EPA approved three types of emission durability programs under these procedures: whole vehicle, full mileage; whole vehicle, accelerated mileage; and bench aging procedures which involved thermal aging of the catalyst plus oxygen sensor system.

9 Reference EPA Guidance Letter No. CD 94 13, " Alternative Durability Guidance for MY94 through MY98", dated July 29,1994. This letter explained that as received, un screened in use data should be compared to vehicles run on the alternative durability program ( ASADP). A " significant majority" of the in use data should be covered by the durability program. We defined the acceptance criteria in that letter as follows: " EPA does not require ASADPs to meet a specific minimum severity level ( or confidence level) because different methods may be used to estimate the degree of severity. ... However, an ASADP would be acceptable to EPA if EPA believes that it were designed to match the in use deterioration of 90 95 percent of vehicles in the engine family."

11 temperature driving modes. It also contains numerous driving modes which do not significantly contribute to deterioration. This makes the process longer but adds little benefit in predicting emission deterioration.

In response to these concerns, EPA began a voluntary emission durability program in the 1994 model year for light duty vehicles. This program allowed manufacturers to develop their own procedures to evaluate durability and deterioration subject to prior Agency approval8. EPA's approval criteria required the manufacturer to demonstrate that the durability procedures would cover a significant majority of in use vehicle's emission deterioration9. One additional condition for approval was that the manufacturer conduct or fund an in use test program to evaluate the effectiveness of its predictions. The initial program was referred to as revised durability program I ( RDP I). It was an interim program scheduled to expire after the 1995 model year and was intended to serve as a bridge to an anticipated 10 Ref. 59 FR 36368 ( July 18, 1994), 62 FR 11082 ( March 11, 1997), 62 FR 11138 ( March 11, 1997) and 62 FR 44872 ( August 22, 1997).

11 An additive DF is calculated by performing a least squares regression of the emission versus mileage data for each exhaust emission constituent and subtracting the 4,000 mile emission level from the full useful life emission level ( historically, 100,000 miles). The DF is then used with emission data from the emission data vehicle to demonstrate compliance with the standards for the purpose of certification. The sum of the emissions from the EDV plus the additive DF is referred to as the certification level and must be less than or equal to the emission standard to receive a certificate of conformity.

12 complete revision to the durability process. The provisions of RDP I were extended in a series of regulatory actions10.

Ultimately, the Agency instituted a comprehensive revision to the durability process as part of the CAP 2000 rulemaking.

For evaporative and refueling emissions deterioration,

EPA allowed manufacturers to develop their own process to either bench age components or do whole vehicle aging, also subject to Agency review and approval. The evaporative and refueling deterioration factor is required to be additive. 11 4. Emission Durability Procedures under CAP 2000 The CAP 2000 rulemaking was a comprehensive update to the entire light duty vehicle certification process. One part of this involved the manufacturer's required demonstration of emission durability. The Agency eliminated the use of AMA for new durability demonstrations. In CAP 2000, the Agency replaced the AMA based durability program with a durability process similar to the optional RDP I program. Each manufacturer, except small volume manufacturers, was required to develop an emission 12 The CAP 2000 regulations " grand fathered" procedures which had been already approved under the RDP provisions. Consequently, these grand fathered procedures were not approved again under the CAP 2000 provisions. [ 63 FR. 39661]

13 Candidate in use vehicles are vehicles selected under the provisions of the in use verification program ( IUVP). This includes mileage restrictions, procurement requirements, and screening requirements designed to eliminate only tampered, mis used or unsafe vehicles. [ Reference: 40 CFR 86.1845 01 and 40 CFR 86.1845 04]

13 durability process which would accurately predict the in use deterioration of the vehicles they produce. The manufacturer had the flexibility to design an efficient program that met that objective.

The manufacturer's plan was then reviewed by EPA for approval12. Approval from the Agency required a demonstration that the durability process was designed to generate DFs representative of in use deterioration. This demonstration was more than simply matching the average inuse deterioration with DFs. Manufacturers needed to demonstrate to EPA's satisfaction that their durability process would result in the same or more deterioration than is reflected by the in use data for a significant majority of their vehicles. Manufacturers were required to provide evidence that their durability process resulted in predicted emission deterioration that were equal to or more severe than the deterioration rates experienced by a significant majority ( approximately 90%) of candidate in use vehicles13.

Furthermore, this demonstration was required to cover the breadth of the vehicles covered by the durability procedure.

This evaluation concerning coverage of a significant 14 majority of the in use data was usually made independently on several potential worst case vehicles which bound the envelope of vehicles covered by the durability procedure.

Manufacturers typically demonstrated that emission deterioration predicted by their durability program would cover approximately 90 percent of the in use population using one ( or more) of the following sources of data: in use emission tests, in use driving characteristics, or in use catalyst temperature measurements. At that time EPA had not developed a specific required method to make this demonstration.

Two major types of durability processes emerged from the CAP 2000 experience: whole vehicle and bench aging processes.

The whole vehicle aging procedures involve driving vehicles on a track or dynamometer on an aggressive driving cycle of the manufacturer's design. In general, the speed,

acceleration rates, and/ or vehicle load are significantly increased compared to the AMA cycle or normal in use driving patterns. The vehicle can be driven either for full usefullife mileage, or, for a higher stress cycle, the vehicle can be driven for a reduced number of miles ( e. g., 1 mile on the high speed cycle equals 2 miles in use). In either case,

the vehicle is tested periodically and a DF is calculated.

The bench aging procedures involve the removal of critical emission components, such as the catalyst and 14 An engine dynamometer bench generally consists of an engine dynamometer, a " slave" engine, and required controllers and sensors to achieve the desired operation of the engine on the dynamometer.

15 Under this alternative, emission components aged to the equivalent of full useful life would be installed on EDVs. The test data from the EDV would then serve to establish the certification level and show compliance with the full useful life emission standards.

15 oxygen sensor, and the accelerated aging of those components on an engine dynamometer bench. 14 During the bench aging process important engine/ catalyst parameters are controlled to assure proper aging. Usually, elevated catalyst temperatures are maintained while fuel is controlled to include lean, rich, and stoichiometric control. Through a series of tests, manufacturers determine the amount of time needed to bench age a catalyst so it is aged to the equivalent of 100,000 miles. In some cases the manufacturer developed the amount of aging time using catalyst temperature data measured on a road cycle. In other cases,

the manufacturer developed the aging time through a trial and error process. Typical bench aging periods are 100 300 hours, although these can vary from manufacturer to manufacturer. Sources of deterioration other than thermal aging can be accounted for by aging the catalyst for an additional amount of time.

The CAP 2000 regulations allow manufacturers to choose from three different methods to demonstrate emissions durability. Manufacturers could calculate additive DFs,

multiplicative DFs, or test EDVs with aged hardware15 16 Reference: 40 CFR 86.1845 01 and 40 CFR 86.1845 04.

17 The Agency may withdraw approval for a durability process if the Administrator determines, based on IUVP or other data, that the durability process does not accurately predict emission levels or compliance with the standards. [ Ref. 40 CFR 86.1923 01 ( h)]. In addition, where the average in use verification data for a test group ( or several test groups) exceeds 1.3 times the applicable emission standard and at least 50% of the test vehicles fail the standard in use, manufacturers are required to supply additional " recall quality" in use data. [ Ref. 40 CFR 86.1846 01]

16 installed on them.

Regardless of whether manufacturers used whole vehicle or bench aging durability procedures, CAP 2000 also required the manufacturer to later collect emission data on candidate in use vehicles selected under the provisions of the in use verification program ( IUVP) 16. Among other uses of the data, the IUVP data must be used by the manufacturer to check on and improve its durability program. The data also is available to assist the Agency to target vehicle testing for its recall program. The Agency may intercede17 when the in use data indicate the durability process underestimates in use emission levels.

The CAP 2000 regulations did not change the previous procedures used to obtain DFs for evaporative/ refueling families.

C. Ethyl petition to reconsider the CAP 2000 rules.

On August 17, 1999, Ethyl Corporation petitioned EPA to reconsider the CAP 2000 regulations. EPA requested public comment on the petition, 64 FR 60,401 ( November 5, 1999 and 64 Fed. Reg. 70,665 ( December 17, 1999), and received 17 comments from various interested parties. After consideration of the petition and of all comments, EPA denied the petition for reconsideration. 66 FR 45,777 ( August 30, 2001).

Ethyl Corporation also petitioned the Agency to reconsider the final rule entitled " Emissions Control, Air Pollution From 2004 and Later Model Year Heavy Duty Highway Engines and Vehicles; Light Duty On Board Diagnostics Requirements, Revision; Final Rule," 65 FR 59896 59978 ( referred to here as the " Heavy Duty Rule"). After consideration of the petition and all of the comments, EPA denied the petition for reconsideration. 66 FR 45,777 ( August 30, 2001).

D. Judicial review of the CAP 2000 rules.

Ethyl Corporation petitioned for review of the CAP 2000 rulemaking, claiming among other things that the CAP 2000 durability provisions were unlawful as EPA had not promulgated methods and procedures for making tests by regulation as required by § 206. [ Ethyl Corp. v. EPA, 306 F. 3d 1144 ( D. C. Cir. Oct. 22, 2002).]

In an opinion issued on October 22, 2002, the Court found that the CAP 2000 regulations did not satisfy the requirements of Section 206( d) of the CAA to establish methods and procedures for making tests through regulation.

The Court recognized that there was an important distinction between an EPA regulation that established 18 general or vaguely articulated test procedures, with more specific details provided in a later proceeding, and a regulation which failed to establish any test procedures at all and only adopted procedures for the later development of tests. The former situation would receive deferential judicial review under the applicable case law. The latter case, however, would fail to meet the requirements of section 206( d). The Court held that the CAP 2000 regulations fell into this latter group, and were improper because EPA itself failed to establish any test procedures at all in the regulation, vaguely articulated or not. EPA's regulation provided only for the manufacturer to develop its own test procedure and submit it for later EPA approval.

This was inconsistent with the scope of section 206( d),

[ Ethyl at 1149 50.]

The Court also said that " nothing in our opinion requires that EPA use only a ' one size fits all' test method. All that is required is that it establish its procedures, no matter how variegated, ' by regulation.'"

[ Ethyl at 1150.]

The Court's decision stated that " CAP 2000, rather than constituting an EPA establishment ' by regulation' of ' methods and procedures for making tests,' as required by section 206( d), is instead a promulgation of criteria for the later establishment of such methods and procedures by private negotiation between the EPA and each regulated auto 19 maker. So it is ' not in accordance with law.'" The Court vacated " the CAP 2000 program" and remanded the case to the EPA with instructions to establish test methods and procedures by regulation. [ Id.]

Since the issue before the Court was the legality of EPA's adoption of the CAP 2000 durability provisions, the court's vacature of " the CAP 2000 program" is limited to vacating the CAP 2000 durability provisions.

The Court also remanded the case to EPA with instructions to establish test methods and procedures by regulation. Today's proposal is the result of the court's decision, and is limited to emission durability procedures.

II. How did EPA develop the proposed durability procedures?

The process and data used to develop the proposed durability procedures is discussed below. Additional data and analysis used by EPA in the regulation development process are contained in the Agency's Draft Technical Support Document ( TSD).

A. What is the purpose of the durability program?

EPA issues certificates of conformity based on testing and other information submitted by manufacturers which verifies compliance with the applicable emission standards over the vehicles' useful life. The durability program is the tool used to adjust low mileage test results from emission data vehicles ( EDV's) to predict emission results 18 Ref. 40 CFR 86.1823 01( b)( 1). The term " candidate in use vehicles" means vehicles which would meet the selection criteria of the in use verification program ( IUVP)).

19 Ref. 63 FR 39660 ( July 23, 1998).

20 at full useful life mileage.

The purpose of the durability program is to provide EPA with reasonable assurance that vehicles covered by a certificate of conformity will, in actual use, comply with the applicable emission standards over their useful life.

We believe that the durability process used to support an application for certification should cover a significant majority of in use vehicles that will be covered by that certificate. In the CAP 2000 rulemaking, EPA established the requirement that manufacturers demonstrate the " adequacy of [ their] durability processes to effectively predict emission compliance for candidate in use vehicles .18" This objective remains in today's proposal.

Production variability or other reasons can lead to differences in actual emission levels among vehicles of the same nominal design. In the CAP 2000 rulemaking, EPA required that a durability program adequately predict emission deterioration for a significant majority of in use vehicles. This was typically approximately 90 percent coverage of the distribution19. In today's proposal we are taking the same approach, such that a durability program is expected to effectively predict a " significant majority",

meaning coverage of approximately 90 percent of the 20 A durability group is the basic classification unit of a manufacturer's product line as defined in § 86.1822 01 21 distribution of in use emission levels and deterioration.

In summary, the objective of the durability program is to effectively predict in use emission deterioration rates and emission levels by covering the significant majority,

meaning approximately 90 percent, of the distribution of emission deterioration of candidate in use vehicles of each vehicle design which uses the durability program.

A durability group20 can include several different vehicle designs which may have different emission levels and deterioration rates. In the CAP 2000 rulemaking, EPA required that the durability data vehicle ( DDV) be the vehicle with the highest expected emission deterioration of the vehicles within the durability group [ ref. 86.1820 01].

( We are not proposing to change the DDV selection criteria in this rulemaking.)

The durability program is used to calculate certification levels either by applying DFs to EDV lowmileage test data or by testing EDVs with aged emission control hardware installed. EPA issues a certificate when the certification levels of the EDV comply with the emission standards. Manufacturers normally design with an additional compliance margin between the standard and the certification level, to address various uncertainties. Especially for EDVs with certification levels at or just under the 21 Engine out emissions are the engine's emissions before they are treated by the catalytic converter or other after treatment emission control devices.

22 Issues related to emissions deterioration for diesel fueled vehicles are discussed in section II E.

23 The technical support document for CAP 2000 proposal can be viewed in docket number A 96 50. The data that supports stable engineout emissions is contained in Appendix I of that document.

22 standards, we believe it is important to have some level of assurance that those levels are indeed predicting the full useful life emission levels of the significant majority of in use vehicles covered by the certificate.

B. What are the factors that affect exhaust emission deterioration?

The first step in developing an exhaust durability program is identifying the significant sources of emission deterioration. Emission levels will increase over mileage if either ( 1) the engine out emissions21 of the engine increase or ( 2) the effectiveness of the exhaust aftertreatment devices decreases.

For all current design light and heavy duty vehicles ( excluding diesel fueled vehicles) the catalytic converter is the only exhaust after treatment device in use22. EPA presented evidence in its draft technical support document for the CAP 2000 proposal23 that engine out emissions exhibit no significant deterioration for these current technology vehicles. This conclusion is also supported by an 24 Reference: " In Use Emissions with Today's Closed Loop Systems" by H. Haskew and T. Liberty of General Motors, SAE No. 910339.

23 Society of Automotive Engineers ( SAE) paper24.

Consequently, the Agency believes that engine out emission increase is not a significant source of emission deterioration. Whatever minor level of deterioration may occur as a result of engine out emission increases, it can be represented by an additional amount of catalyst aging.

The major source of emission deterioration in current technology vehicles today is the loss of catalyst efficiency. The two major sources of this efficiency loss are accumulated thermal exposure and poisoning. Minor sources of deterioration include coating of the catalyst substrate with fuel impurities, and physical deterioration of the catalysts such as the loss of catalytic material.

Loss of effective fuel control due to deterioration of the oxygen sensor can also lead to lower catalyst efficiency as the vehicle ages and, therefore, to increased emission deterioration.

The sources of catalyst poisoning are compounds contained in the fuel and in the lubricating oil ( chiefly lead ( Pb), phosphorus ( P), and sulfur ( S)). EPA has made significant strides to reduce poisons in fuels by fuel regulation, including regulations that have eliminated lead and significantly reduced sulfur levels in automobile fuels.

The Alliance of Automobile Manufacturers ( the " Alliance") 25 Reference: 40 CFR 86.113 04 ( a) ( 3) or 40 CFR 86.113 94 ( a) ( 2)

24 has conducted periodic surveys of fuel used across the United States which have documented the extent of these reductions. Manufacturers generally use representative commercially available fuel for testing and mileage accumulation on durability data vehicles. They are required to do so25 for mileage accumulation on EDVs. Lubrication oils have also improved over the years. While EPA does not regulate the oils, the American Petroleum Institute ( API)

together with the International Lubrication and Standardization and Approval Committee ( ILSAC) have developed voluntary oil certification levels and evaluation procedures. Only oils with the best certification levels are allowed to use the API " star burst" certification mark in packaging and advertisement. Over the years, API and ILSAC have established lower levels of phosphorous with new levels of oil certification. Today the most advanced oils are designated as GF3. Market forces have proven sufficient to encourage manufacturers to market oils that meet the latest API/ ILSAC requirements. Today, almost all of oil used in automobile applications meet the GF3 oil specifications. The advances in oil and fuel formulation have reduced poisoning of the catalyst but have not eliminated it.

Exposure to high temperatures leads to three major 26 References: " Thermal Effect on Three Way Catalyst Deactivation and Improvement" by K. Ihara, K. Ohkubo, and Y. Niura of Mazda, SAE No. 871192 and " High Temperature Deactivation of Three Way Catalyst" by L. Carol, N. Newman, and G. Mann of General Motors, SAE No. 892040.

27 References: " Effect of High Temperatures on Three Way Automobile Catalysts" by R. H. Hammerle and C. H. Wu of Ford, SAE No. 840549; " Thermal Effect on Three Way Catalyst Deactivation and Improvement" by K. Ihara, K. Ohkubo, and Y. Niura of Mazda, SAE No. 871192, and " Thermal Deterioration Mechanism of Pt/ Rh Three Way Catalysts" by S. Matsunaga, K. Yokota, D. Hyodo, T. Suzuki, and H. Sobukawa of Toyota, SAE No. 982706.

25 deterioration mechanisms in catalysts. First, high temperatures cause the coalescence of active material,

called sintering. Sintering reduces the surface area available to perform catalytic reactions. This then reduces the effectiveness of the catalyst. Second, loss of washcoat surface area is also accelerated at high temperatures.

The loss of wash coat surface area is an indirect cause of active material sintering. Finally, high temperatures can promote chemical reaction of one type of active material with another type of active material ( such as the formation of Pt Pd alloy) and with other compounds in the catalyst ( such as the formation of Pt Ni alloy). In their new chemical state the active material is less effective at reducing emissions. It has been widely reported in the technical literature that the effects of high catalyst temperature are cumulative and generally increase exponentially with increased temperature26.

It is also reported in the technical literature that the air/ fuel ( A/ F) ratio in the catalyst can affect the rate of thermal deterioration27. The same temperature exposure 28 Reference: " Operational Criteria Affecting the design of Thermally Stable Single Bed Three Way Catalysts" by B. Cooper and T. Truex of Johnson Matthey, SAE No. 850128.

26 experienced during lean catalyst A/ F ratio causes significantly more deterioration than at rich or stoichiometric operation.

Three way catalysts are only simultaneously effective at oxidizing hydrocarbons ( HC) and carbon monoxide ( CO) and reducing oxides of nitrogen ( NOx) in a very narrow window of catalyst A/ F ratio near stoichiometry28. To maintain the A/ F ratio control needed to assure high catalyst efficiency,

all modern gasoline vehicles use feed back fuel control.

The feed back control system uses an oxygen sensor located just in front of the first catalyst to monitor whether the instantaneous A/ F ratio is rich or lean and a computer engine controller to adjust the fuel system ( in the opposite direction) to move towards stoichiometry. Although the A/ F ratio may be sightly rich or lean at any given second, on a time averaged basis the feed back fuel system is able to control the fuel to very near stoichiometric levels. The oxygen sensor is the critical part of this system and is subject to the same sources of deterioration as the catalyst  thermal exposure, poisoning, physical deterioration, and coating.

Physical deterioration of the catalyst or oxygen sensor such as cracking or loss of the catalyst substrate, are rare events that typically occur because of a faulty design. 27 These concerns are addressed by the component durability feature of the durability program. Under the component durability provisions, manufacturers are responsible to demonstrate using good engineering judgement that all emission related components are durable in the operating environment they will experience throughout the vehicle's useful life.

Coating of the catalyst substrate or the oxygen sensor generally occurs due to contaminants in the fuel. These contaminants are not part of the fuel formulation, but occur by accident due to mishandling of fuel in the distribution process. Coating caused by contaminants in the fuel is beyond the scope of the durability program. On the other hand, coating of the oxygen sensor may also occur due to installation of the oxygen sensor with an improper antiseize compound that contains material that coats the oxygen sensor in actual use. Coating of the oxygen senor in this case should be addressed during the component durability portion of the durability process.

C. The strawman durability procedures In preparing this proposal, EPA initially developed " strawman" durability procedures. The strawman durability procedures contained both whole vehicle and bench aging procedures. A copy of the strawman durability procedure is contained in the TSD. The following discussion summarizes the strawman durability procedures and the development 28 rationale for those procedures.

The strawman proposal was used to solicit feedback from key stakeholders. Today's proposal is based on the strawman durability procedures with adjustment reflecting our response to the comments we received from vehicle manufacturers, emission control equipment manufacturers, and Ethyl Corporation.

1. The whole vehicle aging procedure Sources of emission deterioration on a road cycle Whole vehicle aging consists of running the entire vehicle on a track or engine dynamometer. The vehicle is driven on a road cycle which usually consists of a speedversus time trace with specified acceleration rates, fuel properties, and vehicle load. Vehicles aged using wholevehicle aging procedures experience: ( 1) catalyst thermal deterioration due to the heat generated in the catalyst during vehicle operation, ( 2) poisoning of the catalyst due to the consumption of fuel and lubrication oil, ( 3)

degradation of the accuracy of fuel control, and ( 4)

engineout emission deterioration. Of these four sources of deterioration, catalyst temperature exposure is the predominant source and the easiest to control.

Consequently, once a road cycle has been established that has a reasonable amount of poisoning, fuel control deterioration ( typically from the oxygen sensor), and engine out emissions deterioration, catalyst temperature 29 exposure can be used to adjust the severity of the driving cycle to meet the desired objective.

Poisoning is basically a function of number of miles run and the type and amount of the fuel and lubricating oil which is consumed. Engine out emission deterioration is largely a function of miles run, but as discussed previously, engine out emission deterioration is thought to be near zero. If the road cycle incorporates the full number of useful life miles and the fuel and oil used are representative of in use, poisoning and engine out deterioration should be appropriately accounted for.

As previously discussed, oxygen sensor deterioration is a function of thermal exposure, poisoning, physical deterioration and coating. As discussed above, coating and physical deterioration are rare and more properly addressed by the component durability provisions than the emission deterioration procedures that are the subject of this proposal. Poisoning is caused from ingested oil and compounds in the fuel burned in the engine, the same sources of poisons experienced by catalysts. Addressing the poisoning issues for catalysts will address the same poisoning concerns for oxygen sensors because the sensors are in the same exhaust stream as the catalyst and will experience the same poisons as the catalyst. The remaining source of deterioration of oxygen sensors is thermal exposure. Since oxygen sensors are installed near the 30 catalyst in the exhaust stream they experience the same heat transfer effect from the hot exhaust stream as the catalyst.

Consequently, appropriate control of catalyst temperature during the road cycle will lead to appropriate oxygen sensor deterioration.

Higher catalyst temperatures occur at higher engine speed and engine load. Engine speed and load are higher when vehicle speed, acceleration rates, and vehicle loading are higher. Consequently the speed and acceleration distribution of a road cycle will determine the amount of catalyst temperature and oxygen sensor deterioration.

Developing a standard road ( SRC) cycle to achieve the durability objective An appropriate road cycle is one that meets the severity objective for the mileage accumulation cycle. As discussed previously, the objective of EPA's proposed durability program is to effectively cover a significant majority ( approximately 90 percent) of the distribution of in use emission deterioration of candidate in use vehicles across the entire fleet of vehicles covered by the durability program. In developing a standard road cycle applicable to all manufacturers, the objective encompasses the entire fleet of vehicles.

Once the test vehicle is selected and the vehicle load and fuel specifications are fixed, the only variable remaining that can influence the severity of a road cycle is 31 the speed versus time distribution of the cycle. Simply matching the speed and acceleration distribution of typical or average in use driving is not appropriate, because our objective is ninety percent coverage of the in use emission deterioration. Average in use driving speeds and accelerations represent only fifty percent coverage.

Matching the driving speed and acceleration of the ninetieth percentile driver would not automatically accomplish that objective by itself, because there are additional variables in actual driving that influence the work performed by the engine and, consequently, the rate of emission deterioration. In use driving includes operating the vehicle on various road surfaces ( such as gravel and rough roads), over various road grades ( up or down hills), in various weather conditions ( cold, hot, raining, snowing, and winds), and with various accessories in operation ( such as air conditioning, defroster, and headlights). Directionally,

all of these additional variables result in additional engine work, and consequently lead to higher catalyst temperatures and more emission deterioration than operating the vehicle at the same speed versus time trace on a smooth,

level track or on a dynamometer.

Strawman road cycle EPA developed a strawman version of a standard road cycle based the data available at that time. EPA reviewed speeds and acceleration rates that are typically encountered 29 Reference: " Federal Test Procedure Review Project: Preliminary Technical Report" , EPA publication no. 420 R 33 007.

30 Several approved manufacturer road cycles are discussed in the TSD.

32 in use29 and extrapolated what speeds and acceleration might be typical for the ninetieth percentile driver. As discussed previously, EPA believed that the appropriate speed and accelerations should be higher than the ninetiethpercentile driver due to additional variables seen in actual driving that affect deterioration. EPA also reviewed the speeds and acceleration rates used by manufacturers' road cycles previously approved by EPA under the CAP 2000 regulations ( or approved under the RDP process and subsequently grand fathered into the CAP 2000 program) 30.

To be approved under CAP 2000 or the RDP program, as applicable, the manufacturers provided information that EPA believed showed that these cycles covered the significant majority, approximately 90 percent, of the distribution of emission deterioration rates seen in use on their vehicles.

This would cover deterioration from in use speeds,

accelerations, other driving conditions, vehicle load, fuel,

and the like. EPA developed speeds and acceleration rates for the strawman standard road cycle in the high range of severity compared to the manufacturer specific cycles,

because the standard EPA cycle was to cover the entire fleet of vehicles while the individual manufacturer's cycle was targeted to only cover the breadth of their specific product 31 Assuming a 22 hour workday, it would take 89 days to drive the full useful life miles and 14 days to perform the needed emission tests, for a total of 103 days.

33 line. Consequently, the strawman standard road cycle was conservative and targeted at a higher degree of severity than most manufacturer cycles.

The road cycle developed for the strawman durability procedures is described in the technical support document for this rule.

At the time the strawman road cycle was being developed EPA did not have any catalyst time at temperature data measured on this cycle. This data became available as part of the comments received on the durability strawman proposal. As we will discuss in section II. D., we ultimately revised the strawman road cycle to better achieve our durability target based on this catalyst time

attemperature data. That revised cycle became the standard road cycle that we are proposing today.

Early termination of mileage accumulation One concern with performing mileage accumulation on a whole vehicle over its full useful life period is the amount of time it takes. In the strawman road cycle, running a vehicle for 100,000 miles was estimated to take about 103 days31. For Tier 2 vehicles with full useful life periods of 120,000 or 150,000 miles the time would be even higher ( 120 and 147 days, respectively).

The strawman whole vehicle procedure contained a 32 The 80% statistical confidence limit means that 80% of the time the real deterioration rate would be lower than the extrapolated value.

34 provision allowing manufacturers to terminate mileage accumulation early at a minimum of 75% of full useful life,

and to project the full useful life deterioration factors using the upper 80% statistical confidence limit. This provision is similar to one contained in the RPD I regulations with the added limitation of using the upper 80th% confidence limit. [ Ref. § 40 CFR 86.094 26 ( a)( 4)( i)( B)] It allows manufacturers to reduce the time and money associated with full useful life mileage accumulation. At the same time, it protects the integrity of the deterioration factor by requiring that a higher than average ( upper 80% statistical confidence limit32) DF be projected.

Customization of strawman road cycle We did not include provisions allowing customization of the strawman road cycle, other than to allow for early termination, as discussed above. Before considering customization, EPA needed more information, including data,

on whether or not the strawman road cycle would achieve the durability objective discussed in II B. 1 below. In the strawman proposal, we requested manufacturers to provide catalyst time at temperature data on the road cycle and the manufacturer's approved CAP 2000 durability cycle. We did receive some comparative catalyst data and other comments on 35 the strawman proposal, discussed below, which led us to conclude that it would be appropriate to propose approval criteria allowing customization of the standard road cycle or alternative road cycles.

2. The bench aging procedures Background Bench aging procedures generally involve removing critical emission components, such as the catalyst and oxygen sensor, from the DDV and aging those components in an accelerated manner on an aging bench. The aged components are then either reinstalled on the DDV and emission tests are conducted to calculate a DF, or the EDV is tested with aged components which are directly installed on the test vehicle. In the latter case, the results of EDV testing are used to represent the certification levels without the need to calculate a DF. The objective of the bench aging procedure is to produce the desired target level of deterioration in a much shorter period of time than running a vehicle on a road cycle. If the bench aging is properly conducted then it will yield equivalent results to wholevehicle aging.

Sources of emission deterioration on the aging bench As previously discussed, catalyst thermal exposure is the predominant source of emission deterioration.

Temperature exposure of the catalyst can be more conveniently controlled on an aging bench than other sources 36 of deterioration. On the catalyst aging bench, other sources of deterioration can be accounted for by increasing the amount of thermal aging of the catalyst.

Degradation of the fuel control systems is one additional source of deterioration. It can lead to reduced efficiency of the catalyst and, therefore, to increased emission deterioration. In the modern feed back fuel system the oxygen sensor is the critical emission control component. The oxygen sensor deteriorates due to accumulated thermal exposure as well as other reasons. As with the catalyst, thermal aging of the oxygen sensor can be used to represent all the sources of deterioration of the oxygen sensor.

Using the bench procedures to replicate the emission deterioration seen on the road cycle In summary, a bench aging procedure can use thermal aging of the catalyst plus oxygen sensor [ the " catalyst system"] as a surrogate for whole vehicle aging. By selecting the proper temperatures, amount of aging time, and mix of A/ F ratios, the bench aging procedure can be designed to match the rate of deterioration predicted by a wholevehicle aging cycle, and meet the in use emission performance design objectives expected of the durability program.

The effects of temperature exposure on the catalyst are cumulative and increase exponentially with the temperature. 33 Reference: General Chemistry, by D. Ebbing and M. Wrighton, published in 1990 by Houghton Mifflin Co., Boston.

37 Consequently, it is possible to replace a long period of catalyst exposure at a certain temperature with a shorter period of time at a higher temperature. By applying this principle over the entire range of catalyst temperature exposure, it is possible to represent the entire lifetime of catalyst temperature exposure as a much shorter period of time at a single elevated reference temperature.

Determining the aging time on the bench In 1889, the Swedish scientist Svent Arrehenius developed a theoretical formula, which came to be known as the Arrehenius equation, which relates chemical reaction rates with temperature. The Arrehenius equation is widely cited in chemical technical literature and it is noted that " most chemical reactions closely follow" 33 the equation.

For our strawman procedure, we developed a version of the Arrehenius equation, called the Bench Aging Time ( BAT)

equation. The BAT equation compares the deterioration rates that occur at two different temperatures. The BAT equation allows us to convert a given amount of aging time at one temperature to a lesser time at a higher temperature while maintaining the same degree of emission deterioration.

Since the implementation of the RDP I regulations,

beginning in the 1993 model year, EPA has been evaluating the applicability of the BAT equation to durability 34 Ref. Advisory Circular No. 17 F ( November 16, 1982)

35 The 70 mph AMA is the original AMA promulgated in Appendix IV to Part 86 in 1977. It has a high speed on lap 11 of 70 mph. By policy, EPA had allowed manufacturers to use lower speeds ( as low as 55 mph) on lap 11 of the AMA in response to the 55 mph National Speed Limit which was enacted after promulgation of the AMA cycle in the appendix.

38 demonstrations and experimenting with different coefficients for the equation. EPA also has been approving manufacturerdesigned durability procedures under the RDP I and CAP 2000 procedures. As part of the approval process, EPA required catalyst temperature histograms34 of both the manufacturer's procedures and the 70 mph AMA35. EPA used this data to compare the severity of the AMA and the manufacturer's cycles. In general, we found that the BAT equation predicted a similar ratio of severity ( the manufacturer's cycle divided by the AMA) for different manufacturers.

Also, EPA noted that some manufacturers were also basing their bench cycle aging time calculations on similar principles as the Arrehenius equation and that they had developed coefficients similar to the ones we were using with the BAT equation. The BAT equation that EPA developed for the strawman durability process is discussed in the Technical Support Document for this rule.

To use the BAT equation to select the bench aging time for a given temperature, it is necessary to start with a known distribution of time at temperatures for the catalyst.

The strawman version of the standard road cycle was designed to replicate the appropriate level of aging and it 36 The catalyst thermal reactivity is the " R Factor" in EPA's proposed BAT equation to calculate the bench aging time. It is a measure, determined experimentally, of how sensitive the catalyst is to high temperature exposure. The BAT equation is discussed in more detail in section III of the preamble.

39 specifically targeted catalyst temperature as a method to accomplish the aging. Consequently, the distribution of catalyst time at temperature data on the standard road cycle is an appropriate target for a standard bench aging procedure. Therefore, the strawman durability program used catalyst temperature histograms run on the standard road cycle on the DDV configuration as input to the BAT equation to determine the bench aging time and temperature.

The BAT equation and the Arrehenius equation upon which it is based assume that deterioration is determined strictly based on time at temperature. However, as discussed previously, the A/ F ratio in the catalyst can significantly affect the rate of deterioration that occurs for the same temperature exposure. Catalyst deterioration is highest when the A/ F ratio of the catalyst is lean.

One approach to address the effect of A/ F ratio on aging is to separate the aging time into the three A/ F ratio regimes; rich, stoichiometry, and lean; and consider each sub set separately. Another approach would be to control the proportion of rich/ stoichmetric/ lean operation during bench aging and use a composite value of the catalyst thermal reactivity coefficient36 ( R value) based on that distribution in the BAT equation. Since EPA developed the 37 The RAT A cycle is referenced in " Application of Accelerated Rapid Aging Test ( RAT) schedules with Poisons" by D. Ball, A Mohammed, and W. Schmidt of Delphi, SAE No. 972846; " A Survey of Automotive Catalyst Technologies using Rapid Aging Test Schedules which Incorporate Engine Oil Derived Poisons" by D. Ball, and C. Kirby of Delphi, SAE No. 973050; and " The Effects of Oil Derived Poisons on Three Way Catalyst Performance" by D. Lafyatis, R. Petrow, and C. Bennet of Johnson 40 R value using this composite approach, this is the option we chose for the strawman durability program.

Another variable that effects deterioration is poisoning. Little poisoning occurs on the bench cycle because the duration of the test is short ( typically 100 to 300 hours). Consequently, only a limited amount of fuel is used and little lubrication oil is consumed by the engine.

Nevertheless, although the effect is small, it is important to specify the fuel used. The strawman procedure specified the fuel as normal mileage accumulation fuel, which is representative of commercially available fuel. The strawman procedures did not discuss specifications for the oil to be used on the bench engine. Today's proposal requires that the oil used in the bench engine is to be selected using good engineering judgement.

Controlling the A/ F ratio on the bench [ the strawman bench cycle]

For the BAT equation to work properly, it is necessary to have an appropriate and fixed mix of A/ F ratios experienced in the catalyst. This pre determined mix of A/ F ratios in the catalyst on the aging bench is called the " bench cycle". The technical literature37 discusses one Matthey, SAE No. 2002 01 1093.

38 The TSD presents a study of rich/ stoichiometry/ lean A/ F percentages provided by a manufacturer on one of their vehicles.

41 bench cycle, called RAT A, that has been used to age catalysts on an aging bench. This bench cycle is also used by several manufacturers in their own procedures to conduct bench aging.

The proportion of rich/ stoichiometric/ lean A/ F ratios on the RAT A cycle follows the general trend of A/ F ratios seen in the catalyst in use38. The RAT A cycle has mostly stoichiometric A/ F ratios with a small amount of lean and an even smaller amount of rich operation. The bench cycle does not need to exactly replicate what happens in use, in fact the RAT A cycle does not replicate typical in use A/ F ratios. The BAT equation, with the proper coefficients,

will adjust aging time on that bench cycle to assure that the correct amount of aging occurs. EPA developed the proposed BAT coefficients using catalyst time at temperature data measured on the RAT A cycle. The purpose of the bench cycle is to establish a fixed cycle of A/ F ratios on the bench to eliminate A/ F ratio as an uncontrolled variable. By developing a fixed bench cycle, the reference temperature of the cycle and catalyst time at temperature data are the remaining independent variables to determine aging time on the bench. The bench cycle established in the strawman durability program is a slightly modified version of this 42 RAT A cycle where the time at rich and lean operation was rounded to an even number of seconds.

The strawman durability program bench cycle consists of a 60 second cycle which is defined as follows based on the A/ F ratio of the engine ( which is part of the aging bench)

and the rate of secondary air injection ( shop air which is added to the exhaust stream in front of the first catalyst):

01 to 40 secs 14.7 A/ F, no secondary air injection 41 to 45 secs 13.0 A/ F ratio, no secondary air injection 46 to 55 secs 13.0 A/ F ratio, 4% secondary air injection 56 to 60 secs 14.7 A/ F ratio, 4% secondary air injection Strawman bench aging procedures and equipment The BAT equation uses a specific reference temperature to perform the bench aging time calculation. Because the catalyst temperature varies during the bench cycle, the strawman durability program included experimental procedures to determine the effective reference temperature for the bench cycle. The effective temperature was calculated using the BAT equation and catalyst temperature histogram data measured on the aging bench following the bench cycle.

The BAT equation is used to calculate the effective reference temperature by trial and error changes to the 43 reference temperature ( T r) until the calculated aging time equals the actual time represented in the catalyst temperature histogram.

As previously discussed, the BAT equation is used to take the time at temperature data measured during an approved road cycle and determine the amount of time to age a catalyst system following the bench cycle on the aging bench that is necessary to recreate the deterioration effect of the road cycle's catalyst temperature exposure. The effects of A/ F ratio on the severity of temperature exposure are addressed by the bench cycle's use of an appropriate mix of A/ F ratios on the bench.

There are additional sources of deterioration that occur on the road cycle that are not directly replicated on the bench. Engine out deterioration is one source, but as previously discussed, engine out deterioration is near zero.

Of more significance, a road cycle accounts for more poisoning than the bench aging cycle. To account for the additional poisoning seen on the road cycle, and any engineout deterioration that may exist, the aging time on the bench is increased to replace these shortfalls with additional thermal aging. In the strawman durability bench procedures we addressed the potential shortfall by the use of an " A factor" in the BAT equation. The A factor increases the amount of thermal aging to account for all sources of non thermal deterioration. The strawman 44 procedure specified an A factor of 1.1, which increases aging time by 10 percent. We believe that there is very little deterioration left unaccounted by the BAT equation,

Consequently, we selected an A factor value of 1.1 ( a 10%

adjustment).

The strawman durability procedures contain a description of equipment for an aging bench. Briefly, this includes a slave engine mounted to an engine dynamometer with an engine controller and provisions for secondary air injection. This bench aging configuration has been used by several manufacturers to conduct bench aging. It was also the method of aging that was used with the RAT A bench aging cycle which serves as the basis of the bench aging cycle developed for the strawman.

The strawman bench aging procedures are discussed in more detail in the TSD. Briefly, the bench aging procedures begin by measuring catalyst time at temperature data on the standard road cycle for at least 100 miles. The data collected on the road is proportionally increased to represent the full useful life of the vehicle. The time

attemperature data and the effective temperature of the bench cycle ( determined experimentally using a procedure being proposed today) are entered into the BAT equation to calculate how long to age the catalyst system on the bench.

The catalyst plus oxygen sensor system is installed on the aging bench. An engine controller controls the A/ F ratio, 45 speed, and spark timing of the engine and adds secondary air in front of the first catalyst according to the bench cycle.

The bench cycle is repeated as necessary to conduct aging for the amount of time calculated from the BAT equation.

Using this method, the bench aging procedures can reproduce the emission deterioration seen on any road cycle.

3. Allowable customization of the bench aging procedures The strawman bench procedure allowed the following bench aging variables to be customized by individual manufacturers in order to better achieve the durability program objective.

a. The control temperature of EPA's rapid aging bench cycle. The BAT equation can be used to determine the appropriate aging time for any reasonable temperature experienced on the bench cycle and still provide equivalent aging to the strawman bench aging procedure. Choosing a higher temperature will shorten the aging time, while a lower temperature will lengthen the time. Because the relationship between deterioration and aging temperature is exponential, a small change in temperature will lead to a dramatic change in aging time. For example, changing the effective bench temperature from 800 to 850

C will cut the aging time by more than 50 percent. However, care needs to be taken so that the maximum temperature seen on the bench 46 does not exceed the temperature limit that leads to catalyst damage, generally in the range of 1000 to 1050

C. EPA selected 800

C as approximately the lowest reasonable control temperature which results in a relatively short aging time for many applications and which should keep the catalyst below the damage limit. Manufacturers would be allowed to use 800

C without prior approval. Selection of another value for the control temperature on the bench cycle would allow manufacturers to complete the aging in a shorter period of time, but would have no effect on the amount of deterioration produced by the bench aging when calculating aging time with the BAT equation.

b. The R factor. The R factor represents the catalyst sensitivity to temperature exposure. The catalyst design will affect the R factor. In Appendix IX to the proposed regulations, we discuss how an R factor may be determined for a catalyst. The R factors developed by EPA are based on experience with historical catalysts. An appropriately calculated R factor ( determined using the procedures of Appendix IX on the specific catalyst in question) will improve the accuracy of bench aging to meet the ninety percent deterioration objective.

c. The A factor. The A factor represents how much extra catalyst thermal aging is necessary to reflect the additional catalyst deterioration experienced in use, from causes other than thermal exposure. Manufacturers can 39 A full text of the comments ( to the extent that they are releasable and not claimed as CBI) is contained in the TSD.

47 determine an appropriate A factor based on IUVP or other inuse data. The use of a more appropriate A factor will improve the accuracy of bench aging.

d. Use fuel with additional poisons Catalyst poisoning is a real world source of catalyst deterioration.

The strawman bench aging procedures replace some the deterioration due to poisoning with additional thermal aging of the catalyst, reflected by the A factor. Changing the bench aging to include more poisoning deactivation, e. g. by using fuel with lead, sulfur or phosphorus, would reduce the A factor.

D. Development of today's proposal from the strawman durability procedures.

EPA provided the strawman durability procedures to many interested parties and received comments from a number of them. EPA also met individually with many automobile manufacturers and other parties. EPA refined and changed elements of the strawman durability procedures based on comments that we received from stakeholders on the strawman procedures and our improved understanding of how to accomplish our original objectives for the durability program. The principal comments39 that we received were:

1) The strawman standard road cycle is too severe. 48 It does not match in use distributions of speed and acceleration rates.

2) The road cycle does not have enough fuel cuts to match in use driving experience.

3) Manufacturers should be allowed to use their own durability procedures.

4) The strawman bench aging cycle has a temperature spike occurring at a lean catalyst A/ F ratio, which is not representative of in use driving.

5) The BAT equation generates results that very nearly equal General Motors' own internal calculations.

6) The strawman bench aging cycle should have a defined high temperature value rather than defining the A/ F ratio and secondary air injection rates 7) A defined approach of when and how to use IUVP data to adjust durability procedures is not appropriate.

8) If the IUVP data shows that a manufacturer meets emission standards in use ( because, for example, the manufacturer certified with a sufficient compliance margin,

known as " headroom"), the Agency should not be concerned and should not make decisions based on the accuracy of the certification emission deterioration projection seen in isolation.

9) The public should be provided with sufficient information to duplicate the deterioration results of any manufacturer specific procedures that are CBI. 49 10) The Agency should mandate the public release of all information provided by manufacturers ( required or voluntarily submitted) to obtain approval for an alternative cycle.

1. The durability objective EPA continues to believe that the objective established for the strawman durability program is appropriate. It is the same objective that EPA had stated in the CAP 2000 rulemaking for durability procedures. EPA received no adverse comments on the durability objective when it was presented as part of the strawman durability discussion.

EPA is proposing that the objective of the durability program is to predict an expected in use emission deterioration rate and emission level that effectively represents a significant majority ( approximately 90 percent)

of the distribution of emission levels and deterioration in actual use over the full and intermediate useful life of candidate in use vehicles of each vehicle design which uses the durability program. A significant majority means approximately 90% of the distribution.

2. Cycle Severity for the SRC ( Comments 1 and 2)

Several manufacturers commented that the strawman road cycle was too severe, i. e., that the strawman road cycle produced more emission deterioration than necessary to meet the durability objective of 90 percent effective coverage.

Several manufacturers supplied data that compared the 40 In use emissions information supplied by manufacturers is contained in the technical support document and docket to the CAP 2000 rule 50 thermal severity of their cycle, or a publically available cycle, to the strawman road cycle. The manufacturer cycles used in this comparison, with one exception, have been approved under the CAP 2000 durability regulations. During that approval process, the manufacturers provided information40 that EPA believed showed that the cycles effectively covered approximately 90 percent of the in use distribution of emission deterioration for their vehicles.

The in use data supplied by those manufacturers as part of the RDP I [ IUVP in use data is not yet available] process over several years have demonstrated good compliance with emission standards in use. For the durability programs used in the analysis discussed later in this section, all the inuse data demonstrated at least 90 percent compliance with the standards. Furthermore, the DFs used during certification were, for the most part, significantly larger than average deterioration represented by the in use data.

We also evaluated several of these durability processes using the available RDP in use emission data and, although the amount of data does not meet our minimum data requirement of 20 test vehicles, we have concluded that these processes appear to meet the approval criteria and durability objective being proposed today. Based on these screening criteria, we believe that these durability 41 EPA has pursued remedies whenever a manufacturer's in use data demonstrates that the objective of the durability process was not achieved in actual use.

42 Refer to the TSD for a full presentation of the comparative severity between the strawman road cycle and various manufacturer cycles.

51 processes generally meet the durability objective which is being proposed today41.

Therefore, we would expect that EPA's standard road cycle, if properly targeted to achieve the durability objective, should result in similar catalyst temperature exposure as the manufacturers cycles. The fact that the strawman road cycle proved more severe than the manufacturers' cycles indicated it was also more severe than necessary to meet EPA's durability objective.

The relative severity data supplied42 in the manufacturers' comments showed that the strawman road cycle was about 50 percent more severe than the average manufacturer road cycle. That is, the amount of deterioration from the strawman road cycle was approximately 50 percent more than that of the average manufacturer's road cycle. The data ranged from approximately equal severity,

to the strawman being about twice as severe as the manufacturer's cycle. The results depended on the type of vehicle that was used to make the comparison and the cycle to which it was compared.

This catalyst time at temperature data was not available when the strawman road cycle was being developed. 52 Prior to the availability of this data our estimate of how closely the strawman road cycle achieved the durability objective was based mainly on driving characteristics and extrapolated expected effects on catalyst temperature.

Based on this new data, EPA now believes that the strawman road cycle is too severe compared to the stated objective for the durability program. The Standard Road Cycle ( SRC)

that EPA is proposing today has been modified from the strawman version to reduce its severity and to more accurately achieve EPA's durability objective for the entire fleet of vehicles.

Since the objective of the durability program is to effectively cover a significant majority of emission deterioration, we did not attempt to match average in use speed or acceleration rate distributions. Matching average in use driving experience on the SRC would lead to cycle that only covered 50 percent of the distribution of in use emission deterioration. Consequently, EPA rejected the suggestion that the SRC merely match the in use distributions of speed and acceleration rates. The speeds and acceleration rates of the SRC are generally somewhat higher than average in use data to fulfill our target of effectively covering 90 percent of the population's in use emission levels.

To develop the SRC that EPA is proposing, EPA reviewed those manufacturer cycles which used a speed versus time 43 Refer to the TSD for a description of Toyota's U02 and 9 Lap cycles and Ford's HSC cycle. The GM road cycle was not included in the analysis because it does not involve mileage accumulation based on a speed versus time trace.

53 trace run for the vehicle's full useful life to see how they developed their road cycle to reach an appropriate target level of severity. We reviewed speed and acceleration rates used on the Ford HSC and Toyota's U02 and 9 Lap cycles43.

Each of these cycles contained a high speed driving mode which accounted for over one third of the driving time;

speeds in the high speed mode varied between 60 and 75 mph.

The balance of the cycle time was spent in four lower speed laps which consisted of 30, 40, 50, and 55 mph for the U02 and 9 Lap cycle and 35, 45, 55, and 45 mph [ again] for the HSC cycle.

EPA received catalyst temperature histogram data from General Motors ( GM) which showed that the strawman road cycle produced three temperature peaks with little time at temperatures between these peaks. This contrasted with GM's own cycle which resulted in a more filled out distribution resembling a typical skewed normal distribution. GM commented that the strawman's unrealistic tri modal temperature distribution was caused by the use of a few discrete speed laps rather than a richer mixture of driving speeds and loads that occur in normal driving. EPA agrees with GM's observation that a more filled out distribution of catalyst temperatures is a desirable outcome of a road cycle because it more closely matches a normal in use distribution 44 For most current technology vehicles the engine controller stops fueling the engine when the vehicle is stopping or experiencing a significant deceleration. These events are referred to as fuel cuts.

54 of catalyst temperatures.

Toyota commented that the strawman does not contain enough fuel cuts44. Toyota notes that fuel cuts lead to lean catalyst A/ F ratios which in turn lead to more deterioration than the same temperature exposure at stoichiometric operation. EPA agrees with Toyota that a inclusion of a realistic number of fuel cuts in the SRC is desirable for the reasons discussed above.

Toyota recently re designed their 9 Lap cycle to more closely match in use levels of fuel cuts. They call their new cycle the U02 cycle. To add more fuel cuts to their 9

Lap cycle, Toyota added three to five speed " dips" ( of 5 to 15 mph) to each of the constant speed laps in their cycle.

The U02 also added an over acceleration, coast down event to each of their higher speed modes, such as could occur when merging on to a limited access highway. This event causes high temperature exposure to occur at a lean A/ F in the catalyst.

Ford suggested that EPA use a cycle they recently developed called MOD1. The MOD1 cycle was based on EPA's strawman road cycle but Ford reduced the maximum cruise speed to 80 mph and reduced the high speed acceleration rates to 3 or 4 mph/ second. Based on relative severity data supplied by Honda, the MOD1 cycle is about one third less 45 The manufacturer supplied data showed a range of relative thermal severity ( manufacturer/ strawman) from 105% to 45%, 5 of the 11 data points were in the range of 65% to 60%. The TSD contains the data and has an expanded discussion of our review of the data.

55 severe than the strawman cycle. The MOD1 cycle was slightly higher than midway in severity between the HSC and U02 cycles, less severe than Ford's HSC cycle, and more severe than Toyota's U02 cycle. Based on this data, the MOD1 cycle sits among the manufacturer's approved cycles which have been demonstrated to effectively meet the 90 percent durability target. Consequently, the MOD1 cycle seems to be a well measured step in the right direction for overall severity. However, it did not address Toyota's comments that more fuel cuts were needed, nor GM's comments that a richer mix of speed distribution was desirable.

Although there is a fair amount of variability in the manufacturers' relative severity data, about half of the severity data lie within a close band45. That band of severity included the MOD1 cycle. Consequently, because our target for the standard bench cycle is the same target ( effective coverage of 90 percent) as the manufacturers'

programs, it is appropriate to target near this consensus level of severity.

EPA used all this information to develop the standard road cycle ( SRC) proposed today. The SRC is targeted to effectively cover 90 percent of the distribution of emission deterioration rates that occur on candidate vehicles in use,

across the entire fleet. The speeds and acceleration rates 56 on the SRC are reduced from the strawman proposal. The average speed has been lowered from 51.3 to 46.3 mph, the maximum cruise speed was lowered from 85 to 75 mph, and the acceleration rates for higher speed operation were lowered from 5 to 3 mph/ second.

The SRC also includes more fuel cuts and a broader range of speed operation than seen on the strawman cycle to more closely match in use experience. The number of fuelcut events were increased from 14 to 24 events during the seven laps ( 25.9 miles) of the cycle. The duration of each fuel cut was also increased by employing slower rates of deceleration ( deceleration rates varied between 5 and 8 mph/ s in the strawman cycle and from 1 to 5 mph/ s in the SRC). To expand the speed diversity of the road cycle, the number of different cruise speeds was increased from 6 speeds in the strawman cycle to 11 speeds in the SRC.

3. Alternative and customized cycles ( Comment 3)

Manufacturers suggested that they should be allowed to use their own durability procedures.

Background The CAP 2000 durability procedures required manufacturers to develop their own durability process subject to EPA approval. In the CAP 2000 rulemaking EPA established an objective for the durability process to " predict the deterioration of a significant majority of in 46 Ref. 63 FR 39661 ( July 23, 1998).

57 use vehicles46". In addition to being effective at predicting emission deterioration rates and compliance of candidate in use vehicles, these processes also reduced manufacturers' compliance costs by using methods that were already part of their development process.

Although EPA is proposing standard whole vehicle and bench aging durability procedures, EPA is aware that the standard procedures may not achieve the durability objective, discussed in section II. D. 1., for all manufacturers or for certain vehicle models. Because EPA's standard procedures are targeted to achieve the objective for the overall fleet of vehicles, they may over or underachieve the durability objective for some particular manufacturers or vehicles. For example, certain vehicles may have more available power than the vehicles EPA considered when designing the standard procedures. Such vehicles may be operated more aggressively in use than on the SRC. Similarly, vehicles which have less power may be operated less aggressively than on the SRC. When the standard procedures fail to achieve the durability objective, EPA believes that it is appropriate to allow an alternative process when it is necessary to achieve that objective.

In addition, where the manufacturer durability procedure results in approximately equivalent levels of 58 emission deterioration to those of the SRC being proposed today, the use of those procedures may represent a significant time and/ or cost savings to the manufacturer because they may already be conducted as part of the manufacturer's development process. If a manufacturer can demonstrate that their alternative process is essentially equivalent to EPA's proposed standard road cycle, use of that process would have no effect on the emission compliance determination made during certification.

For these reasons, EPA is proposing that manufacturers may customize the standard EPA whole vehicle and certain aspects of bench aging durability processes. The proposed customization provisions include the ability to use either a " customized SRC" ( the SRC cycle run for a different number of miles) or an alternative road cycle. EPA believes that these options will effectively address some manufacturers'

desire to use the manufacturer specific procedures in the future durability program.

Customization of the SRC includes running the SRC for a shorter or longer period of time than specified and/ or changing the fuel to include poisons such as lead or phosphorus combined with running the SRC for a shorter period of time. Alternatives to the SRC involve road cycles that employ time/ speed traces different than the SRC.

EPA is proposing approval criteria for these customized/ alternative procedures. Any existing durability 59 procedures approved under CAP 2000 would have to be reevaluated and approved under the requirements of the proposed regulations.

Customized/ Alternative Road Cycles To obtain approval of a customized/ alternative road cycle the manufacturer must demonstrate that the durability program will likely achieve the durability objective. As previously discussed, the proposed objective of the durability program is to predict an expected in use emission deterioration rate and emission level that effectively represents a significant majority ( approximately 90 percent)

of the distribution of emission levels and deterioration in actual use over the full and intermediate useful life of candidate in use vehicles of each vehicle design which uses the durability program.

To make the initial demonstration necessary for the Agency to approve a customized/ alternative cycle, EPA is proposing that the manufacturer supply high mileage in use emission data on applicable candidate in use vehicles. The vehicles would be randomly procured from actual customer use, generally with an age of 4 to 5 years and with a minimum of approximately 50,000 miles. They would cover the breadth of the vehicles that the manufacturer intends to certify using the customized/ alternative cycle. Vehicles would be procured and FTP tested as received under the provisions of the IUVP program ( ref: 40 CFR 86.1845 04). 60 Manufacturers could use previously generated in use data from the CAP 2000 high mileage IUVP program or the fourthyear of service RDP " reality check" in use program as well as other sources of in use emissions data for this purpose.

EPA will also consider additional emissions data or analyses that the manufacturer may choose to provide, including data from vehicles which have been screened for proper maintenance and use.

Because historical in use data would be used to approve the manufacturer's durability process for current and future vehicles, it is necessary to limit that data to those that are applicable to the vehicle designs the manufacturer intends to cover with the durability process. Manufacturers must remove from the sample the following types of unrepresentative data: ( 1) data which was collected on an engine/ emission control system which is not comparable to the current production designs, ( 2) data collected on a vehicle design which has been recalled due to a defective emission related part ( unless the recall repair was performed on the test vehicle), or ( 3) data from vehicles that have been operated in an abnormal fashion that has impaired the effectiveness of the emission control system.

In addition, manufacturers may also replace data from previously tested vehicles under the following conditions:

( 1) for in use vehicles which have been primarily operated on high sulfur fuel ( fuel with more than 80 ppm sulfur), if 61 EPA has approved sulfur removal preconditioning the manufacturer may replace the as received testing with a second test conducted after sulfur removal preconditioning has been performed, and ( 2) on a case by case basis, EPA may approve replacing the as received testing performed on a vehicle which displays a MIL light that affects emission results with a second test performed after restorative maintenance has been performed. EPA would consider other exclusions or replacements of data on a case by case basis.

The amount of in use emission data required is based on whether the customized/ alternative cycle is more or less severe than the SRC. In most cases, EPA will accept a minimum of 20 candidate in use vehicles. There is less risk of underestimating actual in use emission levels when the customized/ alternative cycle is more severe than the SRC.

EPA is reasonably confident that the SRC will achieve the durability objective for the general population of vehicles.

Consequently, if the customized/ alternative cycle is significantly more severe than the SRC, EPA may accept less data. Conversely, if the customized/ alternative cycle is significantly less severe than the SRC, EPA may require more data up to a maximum of 30 vehicles. EPA encourages the manufacturer to submit more data than these minimum levels.

The relative stringency of the customized/ alternative cycle compared to the SRC must also be demonstrated. This could be accomplished by an evaluation of the two cycles 62 using catalyst time at temperature data from both cycles and using the BAT equation to calculate the required bench aging time of each cycle. For example, if the BAT equation calculates that 200 hours of aging on the SBC would be necessary to reproduce the thermal exposure of full useful life mileage on the SRC and 170 hours of aging to reproduce the thermal exposure on the customized SRC or alternative cycle, the manufacturer's cycle would be 85% as severe as the SRC ( MFR/ SRC x 100% = ( 170/ 200) x 100%= 85%). This value ( 85%) is the equivalency factor. The 85% equivalency factor means that running a vehicle on the SRC for 85% of the required mileage would result in the same emission deterioration as conducting full mileage on the alternative/ customized cycle.

If emissions data is available from the SRC, as well as catalyst time at temperature data, then that emissions information should be included in the evaluation of the relative stringency of the two cycles and the development of the equivalency factor. For example, if the manufacturer has calculated DFs using both cycles then these values may be compared directly. If the manufacturer cycle generates an additive DF for CO of 0.25 using the SRC and 0.20 using the manufacturer cycle, the manufacturers cycle would be 80%

as severe as the SRC ( Mfr/ SRC x 100% = (. 20/. 25) x 100% =

80%). The equivalency factor is the highest value calculated for the FTP emission constituents. In this 63 example, assuming that the CO value is the highest of HC,

CO, and NOx emission constituents, then the equivalency factor is 80%.

This analysis would demonstrate the relative stringency between the customized SRC or alternative cycle and the SRC.

It would also demonstrate the level of stringency of the SRC and the effectiveness of the SRC in meeting the durability objective. In many cases, especially before experience is gained in using the SRC to develop emissions data or certification levels, the same analysis will be used for demonstrating the relative stringency of the SRC noted above and developing the equivalency factor.

In summary, approval of a customized/ alternative road cycle requires an analysis of whether the cycle will achieve the durability program objective using in use emissions data and an evaluation of the relative stringency of the SRC and the manufacturer's program.

Once the customized/ alternative durability process is approved, EPA is proposing that for each test group the manufacturer must determine, using good engineering judgement, whether to apply the durability procedure to that particular test group. Manufacturers should only apply a durability process to a test group when they determine that the durability objective will be achieved for that test group in actual use on candidate in use vehicles.

Furthermore, EPA is proposing that the manufacturer may 64 make modifications to an approved customized/ alternative road cycle and apply them to a test group, to ensure that the modified cycle will effectively achieve the durability objective for future candidate in use vehicles. The manufacturer would be required to identify such modifications in its certification application and explain the basis for them. Manufacturers must use good engineering judgement in making these decisions. Significant, major, or fundamental changes to a customized/ alternative cycle would be considered new cycles and would require advance approval by EPA.

EPA considered a more objective criteria for approval which would have required manufacturers to demonstrate that the customized/ alternative road cycle resulted in ( 1) a specified percent of the in use emission results that were less than or equal to the certification levels, and ( 2) at least 90 percent of the in use emission data passing the applicable emission standards. However, EPA is not proposing such criteria because of concerns that the restrictions of such objective criteria are not needed to determine whether an alternative/ customized cycle would meet the durability objective, and given the wide variety of circumstances and relevant data that might be employed in making a decision,

it could lead to disapproval of a cycle that would achieve the durability objective. 65 Alternative Bench Procedures EPA believes that every bench aging procedure should be based upon measured vehicle performance on either the SRC or an EPA approved road cycle. It is through the connection to the road cycle that EPA is assured that the alternative bench procedures will result in emission deterioration that achieves our durability objective. The BAT equation will calculate how much aging time is necessary on the bench to result in the same amount of emission deterioration experienced on the road cycle. As previously discussed,

manufacturers must demonstrate that all customized/ alternative road cycles meet the durability objective prior to Agency approval.

EPA believes that customizing certain aspects of the standard bench aging procedure is appropriate if the modified procedure continues to produce the same amount of emission deterioration as the SRC or approved road cycle.

Specifically, EPA believes that customization of the following aspects are appropriate for the reasons discussed below.

a. Increasing the control temperature will reduce the time necessary to age the catalyst system on the bench, but it will not affect the severity of the aging because the BAT equation assures that the thermal aging seen on the road cycle is reproduced on the bench regardless of the effective temperature of the bench cycle. 66 b. EPA believes that an experimentally determined Rfactor using the actual catalyst to be produced is expected to be more accurate than using the standard R factor specified by EPA which was developed to apply to the industry as a whole. EPA is proposing a standard experimental procedure which manufacturers can use to develop a R factor that specifically applies their products.

EPA believes that a R factor developed using this standard process will be more accurate than the standard R factor because its development is based on data generated on the catalyst in question. The procedures for experimentally developing a R factor are presented in Appendix IX of the proposed regulation.

EPA will also consider the use of alternative methods to determine the R factor. To have an alternative method approved by EPA, the manufacturer must demonstrate that the R factor determined by this alternative process results in the same ( or more) emission deterioration than the applicable approved road cycle.

One method to make this demonstration is to determine FTP emission levels from a sufficient number of vehicles to meet the 80% statistical confidence criteria ( discussed below) which have completed whole vehicle aging on the applicable road cycle. These vehicles must represent the breadth of the vehicles to be covered by this alternative method. These results are compared with results from the 67 same ( or a similar) vehicle which was tested with a catalyst system aged on the bench for the amount of time calculated from the BAT equation using the experimentally determined Rfactor To be approved, the emission results from the vehicle with the bench aged catalyst system should be greater than or equal to the emission results for the vehicle aged on the road cycle with a minimum of 80%

statistical confidence.

c. The A factor used in the BAT equation is designed to account for sources of deterioration other than thermal aging of the catalyst that occur in actual use but are not represented by the bench aging process. Determining the Afactor by actual in use data is generally superior to the standard A factor of 1.1.

d. Conducting bench aging using fuel with additional poisons is worst case, consequently it is appropriate to do so without further evaluation by EPA. EPA expects when a manufacturer uses fuel with additional poisons during bench aging, they would also adjust the bench aging time by either calculating a new R factor or a new A factor. In that case,

the approval procedures applicable to changing those factors would also apply.

e. Generally, the SRC is used for generating the catalyst aging temperature histogram data used in the BAT.

Using another road cycle is appropriate if the cycle has been approved as discussed above. The approval process 68 assures that the alternative road cycle is expected to achieve the durability objective. Consequently, using an approved cycle to generate catalyst temperature histogram data is appropriate without further evaluation by EPA.

f. EPA's standard bench cycle was developed to include an appropriate amount of rich, lean, and stoichiometric A/ F operation on the bench for the typical vehicle. However, some vehicles have a fuel control strategy that controls fuel within a narrower band than typically occurs. In those cases, use of the SBC may over or underpredict actual emission deterioration in use. It is also possible that the SBC may result in a proper prediction of in use emission deterioration, but a manufacturer may wish to use another bench cycle for reasons of cost and/ or time savings, because that cycle is performed as part of the manufacturer's development process.

If the manufacturer can demonstrate that bench aging following an alternative bench cycle results in the same ( or more) emission deterioration than the SRC or an approved road cycle ( whichever cycle is applicable), then the use of the alternative bench cycle will maintain or improve the ability to achieve the durability objective. In these cases,

it is appropriate to allow the use of a different bench cycle because the alternative bench cycle will accurately reproduce the emission deterioration seen on a road cycle which meets the durability objective. If a manufacturer 69 uses a different bench cycle, they must also experimentally determine a R factor for the BAT equation. The manufacturer may use EPA's experimental process or another approved method to determine an R factor. [ See paragraph b., above,

for approval criteria to determine a customized R factor]

g. There may be some vehicles for which the BAT equation does not calculate appropriate aging times on the bench, although EPA is not aware of such vehicles at this time. In those cases, it would be appropriate to allow a manufacturer to use an alternative to the BAT equation provided it can demonstrate that bench aging time calculated by this alternative process results in the same ( or more)

emission deterioration than the road cycle upon which it is based.

This demonstration can be made by determining FTP emission levels from a sufficient number of vehicles to meet the 80% statistical confidence criteria ( discussed below)

which have completed whole vehicle aging on the applicable road cycle. These vehicles must represent the breadth of the vehicles to be covered by the alternative cycle. The results are compared with results from the same ( or a similar) vehicle which was tested with a catalyst system aged on the bench for the amount of time calculated from the alternative BAT equation. To be approved, the emission results from the vehicle with the bench aged catalyst system should be greater than or equal to the emission results for 70 the vehicle aged on the road cycle with a minimum of 80%

statistical confidence.

4. The standard bench cycle ( Comment 4)

The standard bench cycle ( SBC) consists of a plot of catalyst temperature and A/ F ratio versus time which is followed during bench aging. As discussed previously, the catalyst temperature and A/ F ratio in the catalyst are the most important variables that affect the thermal aging rate of the catalyst. EPA is using its strawman bench aging cycle as the SBC in today's proposal. As discussed above,

the SBC was developed based on methods reported in the literature which were also used effectively by automobile and catalyst manufacturers in the past.

We received comments that the SBC may not represent the mixture of A/ F ratios seen on certain vehicles during in use operation. Furthermore, there was concern that lean catalyst A/ F ratios occur during the higher catalyst temperatures experienced on the SBC. EPA agrees that the use of certain fuel control technologies, such as A/ F ratio sensors rather than traditional oxygen sensors to control fuel metering and the use of algorithms to predict A/ F ratio so that less switching between rich and lean A/ F ratios is required for effective fuel control, could lead to less variation in A/ F ratios in use. Such vehicles may see less time at lean A/ F ratios in the catalyst. Consequently, those vehicles may be over aged using the SBC. To address this 71 concern, EPA is proposing to allow manufacturers to use a different bench cycle and/ or bench aging time equation than the standard procedure, subject to EPA approval, as discussed above.

5. Bench aging time ( Comment 5)

EPA received a comment that the bench aging time ( BAT)

equation used in the strawman produced results nearly equal to those produced by General Motors' internal calculation.

EPA also received confidential information from a manufacturer that the BAT equation resulted in nearly equal results as their confidential procedures. Based on this positive input, EPA has not changed the BAT equation for today's proposal from the equation used in the strawman durability procedures.

6. Bench Aging Specifications ( Comment 6)

In the strawman durability procedures, EPA defined the high temperature seen on the bench cycle indirectly by specifying the A/ F ratio and the amount of secondary air injection. General Motors ( GM) commented that it would be better to define high temperature directly because the high temperature has a significant impact on the aging that occurs on the aging bench. We agree that directly controlling the high temperature spike is a better procedure.

Based on data from GM, the high temperature is usually 72 about 90

C higher than the lower control temperature. We believe that there will be a similar temperature change on the SBC because it was developed from the RAT A cycle which GM used to generate this temperature data. Based on this data, EPA is proposing that the high temperature control point be 90

C ( ± 10

C) higher than the low temperature control point. In the SBC the lower control temperature is proposed to be 800

C ( ± 10

C) and the higher temperature to be 890

C ( ± 10

C). The specification for the A/ F ratio is now defined as " rich" with the exact A/ F ratio to be selected to achieve the desired high temperature of 890

C.

We also changed the secondary air injection rate from 4% to 3% to match the RAT A cycle which was the basis of the strawman proposal. The higher rate of air injection prompted concerns about the ability to deliver that much air homogeneously across the exhaust flow. The original purpose of the secondary air injections was to assure a lean catalyst A/ F ratio ( how lean was not the issue) and to determine the amount of temperature rise that occurred in the exhaust stream. Now that we are specifying the temperature rise of the exhaust stream directly, it is not necessary to require a particularity high rate of air injection. Consequently we harmonized the amount of secondary air injection with the established RAT A procedure.

7. Adjusting durability procedures based on IUVP data 73 ( Comments 7 and 8)

Manufacturers commented that a defined approach of when and how to use IUVP data to adjust durability procedures is not appropriate. Furthermore they commented that EPA should not be concerned whether the durability process accurately predicts in use emission deterioration if the manufacturer is complying with the standards in use.

The CAP 2000 regulations specified that the in use data collected under the in use verification program ( IUVP)

testing provisions would be used to determine if the manufacturer's durability process was adequately predicting in use emission levels ( ref. 86.1823 01(( g), and ( h)). EPA continues to believe it is very important to compare actual in use emission levels to the emission levels predicted at the time of certification and that this in use information should be used to improve the durability process used to make those predictions.

In the strawman procedures, EPA proposed calculating a least squares best fit in use DF for each durability group using the emission data from the IUVP. EPA suggested in the strawman process that its proposed durability regulation should contain a requirement that the manufacturer correct its durability prediction if the certification DF developed by the process for a specific durability group was significantly different from the in use DF, or if there was a statistically significant general offset trend shown. The 74 strawman proposal did not fully develop the procedures to be used to conduct this analysis. These offsets were to be corrected by either mathematically adjusting the DFs by at least half the difference or increasing the number of miles/ hours run during durability mileage accumulation/ catalyst aging.

The automotive industry commented that it would be very difficult to determine statistical significance, given the limited amount of in use verification data, and that this provision could place an unnecessary burden on those manufacturers who were over predicting, rather than underpredicting emission deterioration. They also commented that as long as the in use data was indicating that their vehicles were meeting the emission standards in use, that it should not be a concern to the Agency if the rate of deterioration calculated at the time of certification does not match that of in use vehicles. They recommended that EPA retain the CAP 2000 regulations whereby the in use verification data must be taken into consideration when deciding if the durability process is adequately predicting emission deterioration.

EPA agrees that the approach taken in the CAP 2000 rulemaking is appropriate, because it provides a reasoned framework for when to require analysis and review by manufacturers, and provides the needed discretion for deciding when approval for a program should be withdrawn or 47 Ref. 63 FR 39663 75 modifications required. EPA still has the same concerns about durability accuracy expressed during the CAP 2000 rulemaking: " An accurate durability process facilitates a more meaningful certification process which identifies noncompliance before the vehicles are produced and avoids excess in use emissions. The in use verification program is a tool which can be used by the Agency and the manufacturers to improve the durability process and avoid excessive emissions in use and costly recalls." 47 It is the Agency's expectation when it issues an approval that a durability program will achieve the durability objective in use. EPA expects manufacturers to use the results of the IUVP testing to improve their durability projections when necessary to better achieve the durability objective.

As in the CAP 2000 program, EPA is proposing to require manufacturers to conduct an analysis of their durability program if certain objective criteria discussed below are met. In addition EPA may require such an analysis on a case by case basis even if the criteria are not met. EPA also reserves the authority to withdraw approval of a durability program or require its modification if it determines that the manufacturer's program does not meet the objectives for a durability program.

The Agency is proposing to continue the requirement established in the CAP 2000 rule for the manufacturer to 76 reevaluate the validity of a durability process in achieving the durability objective by performing an analysis when the average IUVP data exceeds 1.3 times the applicable emission standard and at least 50% of the test vehicles fail the standard in use ( evaluated independently for all applicable emission constituents). These proposed analysis trigger criteria are intentionally loose enough to require an analysis only in cases where it is highly likely that durability programs that were failing to meet the durability objective. The Agency is also proposing that it may, at its discretion, require manufacturers to analyze available IUVP data, or other information, when it appears that the durability objective is not being achieved for some portion of the fleet of vehicles covered by a durability procedure regardless of whether the analysis trigger criteria have been met.

As part of the analysis, the manufacturer should address the applicability of the data to current vehicle designs and to the current durability procedures used by the manufacturer. Manufacturers may remove from the sample the following types of unrepresentative data: ( 1) data which was collected on an engine/ emission control system which is not comparable to the current production designs, ( 2) data collected on a vehicle design which has been recalled ( voluntarily or otherwise) due to a defective emission related part ( unless the recall repair was performed on the 77 test vehicle), or ( 3) data from vehicles that have been operated in an abnormal fashion that has impaired the effectiveness of the emission control system. In addition,

manufacturers may also replace data from previously tested vehicles under the following conditions: ( 1) for in use vehicles which have been primarily operated on high sulfur fuel ( fuel with more than 80 ppm sulfur), if EPA has approved sulfur removal preconditioning the manufacturer may replace the as received testing with a second test conducted after sulfur removal preconditioning has been performed, and ( 2) on a case by case basis, EPA may approve replacing the as received testing performed on a vehicle which displays a MIL light that affects emission results with a second test performed after restorative maintenance has been performed.

EPA would consider other exclusions or replacements of data on a case by case basis. The manufacturer may also provide additional in use data with the analysis.

As in the CAP 2000 program, EPA is proposing that it may withdraw approval of a durability program or require its modification if it determines that the program does not meet the objectives for a durability program. In those cases, the Agency is proposing to give the manufacturer a preliminary notice at least 60 days prior to rendering a final decision to withdraw approval for or require modifications to a durability procedure. EPA may extend the 60 day period upon request by a manufacturer when it is necessary to complete a 78 thorough analysis. During this period the manufacturer may submit technical discussion, statistical analyses,

additional data, or other information that is relevant to the decision. This may include an analysis to determine whether factors other than the durability program, such as part defects, are the source of the problem. The Administrator will consider all information submitted by the deadline before reaching a final decision. A final decision to withdraw approval or require modification to a durability procedure would apply to future applications for certification and to the portion of the manufacturer's product line ( or the entire product line) that the Administrator determines to be affected.

These proposed requirements would apply to the EPA standard road and bench durability procedures as well as customized/ alternative durability procedures.

If the manufacturer was using the standard road cycle or standard bench cycle, EPA would require the manufacturer to adjust the durability process so it would achieve the durability objective. The Agency is proposing two options in this situation: ( 1) increasing future DFs by the average percent difference between certification levels and IUVP data, or ( 2) increasing the whole vehicle miles driven or catalyst aging time by the average percent difference between certification levels and IUVP data. Additionally the manufacturer may obtain approval for a new alternative 79 durability process that has been demonstrated to meet the durability objective. If the data set used in the analysis contains less than 20 pieces of data, the Administrator may reduce the degree of adjustment required to account for uncertainty in the data.

If EPA determines that the SRC or the standard durability bench procedures generally do not meet the durability objective for a large number of manufacturers,

EPA will adjust the standard procedures by rulemaking.

As with the criteria for original approval of an alternative durability program, EPA considered a more stringent objective criteria for using IUVP data to evaluate durability procedures which would have required manufacturers to demonstrate that the durability procure resulted in ( 1) in use emission results that are at least a specified percent less than or equal to the certification levels, and ( 2) at least 90 percent of the in use emission data that pass the applicable emission standards. EPA is not proposing such criteria for the reasons described above regarding approval criteria.

8. Reproducibility by outside parties ( Comment 9)

We received comments supporting the goal that the public should be provided sufficient information to duplicate the deterioration results of any manufacturerspecified procedures that are CBI.

In some cases, manufacturers have claimed that certain 48 Refer to section II D 2 for a discussion of how to calculate the equivalency factor.

80 aspects of their manufacturer specific durability procedures are confidential business information ( CBI). As discussed above, the approval process for all alternative cycles includes a determination of the relative severity of the alternative cycles compared to the SRC by means of the calculation of an equivalency factor48.

EPA believes that a manufacturer's equivalency factor should not be considered confidential business information.

The equivalency factor is developed using EPA prescribed methods so there is no manufacturer practice to be protected. The factor relates to how much driving on the SRC is required to meet the durability objective. The SRC is a publically available cycle developed by EPA. Furthermore,

knowing that a certain amount of driving on the SRC produces the same amount of in use emission deterioration as on the manufacturer cycle would not reveal any potentially confidential aspects of the manufacturers in house durability procedures. For example, there would be many different road cycles that would result in the same equivalency factor to the SRC. EPA invites comment on whether the equivalency factor should be eligible for CBI treatment, including any justification for treating it as confidential. In the absence of a compelling justification to treat this equivalency factor as CBI, EPA intends to 81 determine that a manufacturer's equivalency factor would not be considered CBI. Furthermore, EPA intends to publish a list of manufacturers which have obtained approval to use alternative cycles together with a manufacturer's equivalency factor for each test group which uses those cycles.

The equivalency factor will provide the public with sufficient information to duplicate the amount of deterioration produced by a manufacturer specific procedure.

Even if a manufacturer asserts that their cycle is CBI, the public will have a pre determined amount of mileage accumulation on the SRC that will result in an equivalent amount of emission deterioration. Consequently, any interested party could run the SRC for the appropriate number of miles and get the same results that the manufacturer developed during certification.

To reproduce the deterioration generated by a manufacturer which certified using a customized road cycle,

standard bench procedure, or alternative bench procedure, an outside party may run a vehicle using the SRC for the number of miles indicated by the equivalency factor.

Similarly, an outside party will be able to perform bench aging using the SBC. The aging time may be calculated using the BAT equation and measured catalyst temperature on the SRC ( with full useful life mileage adjusted by the equivalency factor). 82 9. Confidentiality of emission test results submitted under the durability program.

Under the durability regulations, a variety of provisions require manufacturers to submit to EPA the results of emissions testing. For example, emissions test results are submitted as part of the approval process for alternative driving cycles. They may also be submitted subsequent to approval as part of an analysis of whether an alternative durability program continues to meet the objective of the durability program. The results of emissions testing are also submitted to EPA as part of the IUVP and confirmatory testing programs. Emissions test results would be submitted to EPA under 40 CFR 86.1823( e)( 1)( A), 86.1847( b)( 1), and ( f)( 1). Emissions test results may also be submitted to EPA under other provisions of the durability regulation.

EPA believes that the results of this emissions testing would be emissions data as defined by 40 CFR 2.301.

Emissions data are not eligible for confidential treatment.

40 CFR 2.301( e). EPA invites comment on why these data should be eligible for CBI treatment. In the absence of a compelling justification received during the comment period,

EPA intends to release emissions test results submitted to EPA as noted above. EPA is not attempting at this time to decide what other data, if any, would be emissions data under 40 CFR 2.301. 83 E. Diesel Vehicle Exhaust Deterioration EPA expects that diesel fueled vehicles will be largely driven in the same fashion as gasoline fueled vehicles. The SRC was developed to include sufficient amount of high catalyst temperature to age the catalyst on an Otto cycle engine. However, the same operation that causes high temperatures in catalysts also causes high engine load and high in cylinder temperatures which increase engine wear in diesel vehicles and lead to emission deterioration. The SRC also contains a reasonable amount of slower speed operation and coast downs followed by deep accelerations which increase lubricating oil consumption, fuel injection deterioration, and increase particulate formation. For these reasons, the SRC is considered to be fuel neutral,

that is, appropriate for any motor vehicle, regardless of the fuel used. Thus, the SRC may be used to evaluate exhaust emission deterioration of vehicles using any fuel.

Furthermore, the provisions to customize the SRC or develop an alterative road cycle would for the same reason apply equally to vehicles, regardless of the fuel used.

The same is not true for bench aging procedures,

however. The bench procedures are only applicable to vehicles which use a catalyst as the principal exhaust emission control strategy. The proposed bench procedures accelerate the normal vehicle aging process by increasing the thermal aging of the catalyst. This strategy will not 84 work acceptably for vehicles that do not have a catalyst,

rely significantly less on the catalyst to provide emission reduction, or use after treatment devices that are significantly different from catalysts used on gasolinefueled vehicles, e. g. NOx adsorbers or catalyzed particulate filters. For that reason the bench procedures proposed today are not applicable to diesel vehicles.

As of the date of this proposal, EPA is not aware of any effective bench aging process for diesel vehicles. At a later date, EPA may choose to propose regulations providing bench aging procedures applicable to diesel fueled vehicles.

In the meantime, diesel fueled vehicles must use the proposed whole vehicle exhaust durability provisions.

F. Evaporative and refueling durability procedures The CAP 2000 regulations for evaporative and refueling emission deterioration procedures are similar to the exhaust durability regulations, in that manufacturers had to propose a durability process for EPA approval. Our proposal incorporates procedures for determining evaporative and refueling emission deterioration levels.

The proposed objective for the evaporative and refueling deterioration programs is the same one proposed for exhaust durability: to predict the expected evaporative and refueling emission deterioration of candidate in use vehicles over their full useful life, covering a significant majority of deterioration. [ Ref 40 CFR 86.1824 01 for 85 evaporative emissions and 40 CFR 86.1825 01 for refueling emissions].

Unlike durability procedures to determine exhaust emission deterioration, EPA has never specified a standard procedure to determine evaporative emission deterioration.

Instead, manufacturers were required to report to EPA evaporative deterioration factors that were " designed and conducted in accordance with good engineering practice".[ ref. 86.091 23( b)( 2)]

Since evaporative and refueling emissions are controlled by a similar vapor control system, the deterioration rates for evaporative and refueling emissions are generally determined using the same methods. Most vehicles use integrated refueling systems where a single charcoal canister handles both evaporative and refueling emission control.

The factors affecting deterioration of evaporative control systems are different from those of exhaust emission systems. Evaporative and refueling emissions are controlled primarily by an activated carbon canister. The canister stores the hydrocarbon ( HC) fumes coming from the vehicle's fuel tank and fuel system. While the engine is running, the HC is purged from the canister and ingested by the engine.

Other components which control evaporative emissions include fuel hoses and lines and the gas tank cap.

To predict evaporative emissions deterioration, it is 49 Refer to " Fuel Permeation Rates of Elastomers after Changing Fuel" by R. Stevens and R. Fuller of Dupont Dow, SAE No. 970307 86 necessary to assess the useful life performance of these vapor control components. Sources of potential deterioration are deactivation of the carbon in the canister, loss of carbon from the canister, degradation of hoses and lines due to environmental conditions ( such as temperature extremes and exposure to ozone, ultraviolet light, and vibration), and fuel cap deterioration due to wear.

Vehicle operating events that may lead to deterioration of the vapor control system include, ( 1) cycling of canister loading due to diurnal and refueling events, ( 2) vibration of components, ( 3) deterioration of hoses due to environmental conditions, and ( 4) deterioration of fuel cap due to wear.

In addition, hosing used in fuel lines are subject to " permeation"  fuel vapors which seep out of microscopic pores in the material. Emissions due to permeation through the hoses generally stabilize after about a month of use and hence do not generally affect the long term deterioration of the evaporative system. 49 Beginning with the 2004 model year, EPA's " Tier 2" regulations include new, more stringent evaporative emission standards. Concern about the permeability effect of alcohol fuels on hoses and other evaporative components led EPA to require that manufacturers 50 Numerous SAE papers examine the permeability of fuel and evaporative system materials as well as the influence of alcohols on permeability. See, for example SAE Paper Nos 910104, 920163, 930992, 970307, 970309, 930992, and 981360.

51 Based on 7 to 10 years of use the number of lifetime diurnals would range from 2000 to 3500 events.

87 account for this effect in developing their evaporative durability processes [ ref. 86.1824 01( a)( iii), ( iv) and ( v)] 50.

Most of the potential causes of vapor control system deterioration are based on time rather than miles driven.

Canister loading is caused mainly by diurnal events, the heating/ cooling cycle that occurs over a 24 hour day. For that reason, it is difficult to compress a full lifetime of diurnal events into a reasonable period of time on a whole vehicle.

It is also desirable for cost reasons to combine a whole vehicle based evaporative/ refueling deterioration evaluation with the whole vehicle exhaust durability program to save the expense of running two separate programs. For exhaust deterioration the important parameter is miles traveled following the SRC, for vapor control deterioration canister loading and purge events are more important. The whole vehicle exhaust durability program is generally completed in about 100 days. During that time, the vehicle would experience about 100 diurnals ( one per day), which is much less than experienced during the vehicle's full useful life. 51 A vehicle aged on the SRC would experience 52 Refer to the TSD for a study of DFs for evaporative emissions. Most DFs were zero, the 70 percentile DF was 5% of the standard.

88 approximately the correct number of refueling events. While this shortfall in diurnal events could theoretically affect projections of deterioration, in actuality, the overall vapor control deterioration is so small that it does not significantly impact the deterioration rate calculation.

Manufacturers have stated that evaporative emissions over the life of a vehicle do not generally increase. An EPA study of evaporative and refueling certification deterioration factors for the 2002 and 2003 model years shows that these DFs are zero or close to zero for many vehicles. 52 When there are evaporative or refueling failures in use, these failures can generally be attributed to failed parts or improper design rather than gradual increases in emissions due to deterioration.

EPA is proposing that manufacturers may determine their evaporative/ refueling deterioration by adding evaporative and refueling tests to the SRC or an approved whole vehicle exhaust durability program. EPA is making this proposal knowing that the road cycle will not include a full lifetime of diurnal events. In making this decision, EPA is relying on the fact that the deterioration rates of current design evaporative system is very small and a more comprehensive procedure would not significantly improve the accuracy of predicting deterioration, but could significantly increase 89 costs.

EPA is also proposing that the evaporative/ refueling deterioration may also be measured using a bench procedure.

EPA is proposing that manufacturers evaluate the effects of certain sources of deterioration in the bench procedure.

The manufacturer should establish a evaporative/ refueling durability program that effectively covers a significant majority ( approximately 90 percent) of in use emission deterioration. A manufacturer may determine certification levels using a bench procedure when it determines ( using good engineering judgement) that the bench procedure is more accurate than the SRC to achieve the durability objective.

While the manufacturer does not need to submit their bench durability procedures for approval, EPA may review any certification level submitted during certification for its appropriateness. EPA is not promulgating specific methods to perform these evaluations. The emission deterioration sources that are proposed to be evaluated in the bench durability procedure are: