[Federal Register: January 17, 2006 (Volume 71, Number 10)]
[Rules and Regulations]
[Page 2809-2842]
[DOCID:fr17ja06-9]

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Part IV

Environmental Protection Agency

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40 CFR Part 86

Emission Durability Procedures and Component Durability Procedures for
New Light-Duty Vehicles, Light-Duty Trucks and Heavy-Duty Vehicles;
Final Rule and Proposed Rule

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 86

[FRL-8019-2]
RIN 2060-AK76

Emission Durability Procedures for New Light-Duty Vehicles,
Light-Duty Trucks and Heavy-Duty Vehicles

AGENCY: Environmental Protection Agency.

ACTION: Final Rule.

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SUMMARY: This final 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 defines
procedures to be used by manufacturers to demonstrate the expected rate
of deterioration of the emission levels of their vehicles.

DATES: This rule is effective February 16, 2006. The information
collection requirements of this rule have been approved by OMB and are
effective February 16, 2006.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. OAR-2002-0079. All documents in the docket are listed in the
EDOCKET index at http://www.epa.gov/edocket. Although listed in the

index, some information is not publicly available, i.e., CBI or other
information whose disclosure is restricted by statute. Certain other
material, such as copyrighted material, is not placed on the Internet
and will be publicly available only in hard copy form. Publicly
available docket materials are available either electronically in
EDOCKET or in hard copy at the Air Docket, EPA/DC, EPA West, Room B102,
1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays. The telephone number for the Public Reading Room is
(202) 566-1744.

FOR FURTHER INFORMATION CONTACT: General Contact: Linda Hormes, Vehicle
Programs and Compliance Division, U.S. EPA, 2000 Traverwood, Ann Arbor,
Michigan 48105, telephone<PHONE_NUMBER>, E-mail<EMAIL_ADDRESS>    Technical Contact: Linc Wehrly, Vehicle Programs and Compliance
Division, U.S. EPA, 2000 Traverwood, Ann Arbor, Michigan 48105,
telephone:<PHONE_NUMBER>, E-mail<EMAIL_ADDRESS>
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
    E. Applicability of the NPRM preamble discussion
    F. Supplemental notice regarding component durability
II. Summary and Analysis of Comments
    A. The Durability Objective
    B. Evaluation of the certification durability procedures based
on in-use emissions data
    C. Standard whole vehicle durability procedure
    1. Standard Road Cycle (SRC)
    2. Vehicle ballasting on SRC mileage accumulation
    3. Calculating the DF from mileage accumulation of 75% of full
useful life mileage
    4. Testing required for DF calculation
    5. Use of an engine dynamometer to recreate the aging on the SRC
    D. Standard Bench Aging Procedure
    E. Catalyst time-at-temperature data measurement
    F. Customized/Alternative durability procedures
    1. Equivalency factors and alternative road cycles
    2. Bench durability aging
    3. Approval of customized/alternative durability procedures
    4. Experimentally determining a customized R-factor
    5. Alternative bench aging cycle content
    G. Component Durability
    H. Minor modifications to approved durability procedures
    I. Required notification to EPA that an approved durability
procedure will be used for a particular durability group
    J. Public Availability of the equivalency factor and supporting
data
    K. Carryover
    L. Evaporative Durability Procedures
    M. Starting model year for the rule
    N. Special provisions for new manufacturers
    O. Delete incorrect reference to intermediate useful life
standards for the evaporative and refueling durability objective
III. What is EPA promulgating 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 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 final rule
    B. Environmental impacts
V. What are the Statutory and Executive Order Reviews for this 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 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
    J. Congressional Review Act

I. Background

A. 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] 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 trucks.\1\ These certification regulations are
known as ``CAP [Compliance Assurance Program] 2000''.\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.
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    \1\ Separate certification regulations exist for heavy-duty
highway vehicles and engines, which refer to the light-duty
certification procedures. Today's final rule will apply to those
subsets for 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 these
regulations.
    \2\ 63 FR 39654 (July 23, 1998).
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    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 over the entire time period of the
vehicles' useful life.\3\
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    \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.
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    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 demonstration.\4\ Today's final rule specifies the methods
that manufacturers must use to determine emissions deterioration for
the purpose of certification.
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    \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 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.
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    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 final rule in context.

B. Durability Demonstration Process History

1. Durability Demonstration Methods Used Prior to the CAP 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 mileage.\5\
This was to simulate the real-world aging of the vehicle's emissions
control systems over the useful life.
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    \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.
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    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 DFs \6\ to
project the emissions levels at full useful life (referred to as the
``certification levels''). The certification levels had to be at or
below the applicable emission standards in order to obtain a
certificate of conformity.
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    \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.
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    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 outdated \7\.
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    \7\ Reference: 63 FR 39653, 39659 (July 23, 1998) (CAP 2000
NPRM).
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    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 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
approval.\8\ EPA's approval criteria required the manufacturer to
demonstrate that the durability procedures would cover a significant
majority of in-use vehicle's emission deterioration.\9\ 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
complete revision to the durability process. The provisions of RDP I
were extended in a series of regulatory actions.\10\ Ultimately, the
Agency instituted a comprehensive revision to the durability process as
part of the CAP 2000 rulemaking.
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    \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 ceriteria 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.''
    \10\ Ref. 59 FR 36368 (July 19, 1994), 62 FR 11082 (March 11,
1997) 62 FR 11138 (March 11, 1997) and 62 FR 44872 (August 22,
1997).
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    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\
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    \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.
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2. 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 requirement for 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 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 approval.\12\
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 in-use 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 vehicles.\13\
Furthermore, this demonstration was required to cover the breadth of
the vehicles covered by the durability procedure.
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    \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]
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    This evaluation concerning coverage of a significant 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 useful-life 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 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.
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    \14\ An engine dynamometer bench generally consists of an engine
dynanometer, a ``slave'' engine, and required controllers and
sensors to achieve the desired operation of the engine on the
dynanometer.
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    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 hardware \15\ installed on them.
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    \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.
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    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 intercede \17\ when the in-use data

indicate the durability process underestimates in-use emission levels.
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    \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].
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    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 60401 (November 5, 1999 and 64 FR 70665 (December 17, 1999), and
received comments from various interested parties. After consideration
of the petition and of all comments, EPA denied the petition for
reconsideration. 66 FR 45777 (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 45777 (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 Sec.  206. [Ethyl Corp. v.
EPA, 306 F.3d 1144 (DC 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 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.]
    Since the issue before the Court was the legality of EPA's adoption
of the CAP 2000 durability provisions, EPA believes 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 final rule
is the result of the court's decision, and is limited to emission
durability procedures.

E. Applicability of the NPRM Preamble Discussion

    Unless otherwise indicated below, the discussion presented in the
preamble to the notice of proposed rulemaking published at 69 FR 17532
is applicable to this final rule.

F. Supplemental Notice Regarding Component Durability

    The Agency received a comment from Afton Chemical Corporation
(``Afton,'' formerly known as Ethyl suggesting that EPA did not address
the component durability portion of the emission durability process and
should establish a procedure for determining component durability.
After the Court decision which remanded EPA to write new regulations
regarding emissions durability, EPA discussed with the Petitioner and
automotive manufacturers the ramifications of that decision. To aid in
these discussions, EPA provided a draft ``mark-up'' version of the CAP
2000 regulations, showing via stricken text exactly which regulations
we believed had been vacated.\18\ We did not strike out the regulatory
language regarding component durability. At that time, neither the
petitioner nor the automotive manufacturers spoke out in opposition to
this. We did not propose new procedures for component durability and
proceeded with the proposed durability regulation, which retained the
``good engineering judgment'' language for component durability.\19\
Today's final rule includes only procedures for the emission
deterioration portion of the durability process, because our
understanding was that component durability was not at issue. However,
Afton's comments are significant enough, that we believe it is
appropriate to take the opportunity for further comment on component
durability regulations. We believe it is appropriate, given the need
for notice and comment for all interested parties, that we treat
component durability in a separate action. Therefore, in addition to
today's final rule, EPA is also today publishing a separate
Supplemental Notice of Proposed Rulemaking requesting comments on a
proposal which addresses component durability. Today's final rule has
not revised the regulatory language for component durability.
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    \18\ A copy of the strike-out version of CAP 2000 language is
included in the Docket to this regulation.
    \19\ Ref. 69 FR 17533 ``EPA is not proposing to change the
existing regulations for determining emission-related component
durability''.
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II. Summary and Analysis of Comments

    EPA received comments from the automotive makers Ford, Volkswagen
and Cummins, two automotive trade associations on behalf of their
member automotive companies, the Afton Chemical Corporation (formerly
know as the Ethyl Corporation), and one comment from a private citizen.
    The comments have been grouped together by subject matter. The
following discussion presents the summary of EPA's proposal, of the
comments received on that proposal, and EPA's response to those
comments.

A. The Durability Objective

    Summary of proposed rule. The proposed rules included a provision
that defined the durability objective [Ref 40 CFR 86.1823-08(a)] as
follows: ``The durability program must 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 \20\
of each vehicle design which uses the durability program.''
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    \20\ Candidate in-use vehicles are vehicles selected under
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]
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    Summary of Comments. The Alliance and AIAM commented that the
phrase ``approximately 90 percent'' could

effectively increase the stringency of the standards by ignoring
whether vehicles are passing the standards in-use and focusing on the
probability distribution that in-use emissions exceed the emission
levels projected at certification. This represents a substantial and
unnecessary departure from the CAP 2000 rules. Instead, the rules
should be in line with the ``significant majority'' goal espoused in
CAP 2000 and the RDP guidance letter (CD-94-13, July 29, 1994).
    In response to a request by EPA to clarify their comments, the
Alliance stated that they were concerned that the proposed provision in
the regulations themselves which defined ``significant majority'' to
mean ``approximately 90 percent'' could be interpreted to establish an
inflexible percentage criterion and eliminate EPA's discretion to
consider other factors when evaluating the effectiveness of a
manufacturer's durability program taken as a whole.
    Response to Comments. 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 full useful life. As discussed
in the 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
candidate in-use vehicles. In the CAP 2000 program, EPA had typically
considered ``significant majority'' to mean approximately 90 percent
coverage of the distribution of in-use deterioration. This concept was
discussed in the preamble to the CAP 2000 rule \21\; however, EPA had
not set a strict numerical criteria in the CAP 2000 regulations.
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    \21\ Ref. CAP 2000 NPRM preamble 63 FR 39661.
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    It was not the EPA's intention to establish in this rule a single
rigid method or an inflexible numerical criteria to evaluate the
durability objective. EPA understands the Alliance's concerns that the
proposed language might lend itself to a more rigid interpretation that
may limit EPA discretion and/or impose unintended burdens on
manufacturers. Consequently, EPA has removed the parenthetical phrase
``approximately 90 percent'' from the finalized durability objective
language in the regulations.
    By making this change we are not relaxing the requirement. The
manufacturer must still demonstrate that a customized/alternative
durability procedure is expected to effectively represent a significant
majority of the distribution of emission deterioration in actual use to
obtain EPA approval to use the procedure for certification. EPA and the
manufacturers will still review IUVP data and/or other data to
determine if the durability objective was achieved in use and whether
it is appropriate to continue to use that durability process for future
certification requests. EPA will consider a variety of different
evidence and/or analyses that the durability objective has been or is
expected to be achieved. However, a demonstration that approximately 90
percent of the distribution of in-use emission deterioration or
emission levels is effectively represented by the durability procedure
will continue to be a satisfactory showing for this purpose.
    The following section discusses how the durability objective will
be used to evaluate certification durability procedures based on in-use
emission data.

B. Evaluation of the Certification Durability Procedures Based on In-
Use Emissions Data

    Summary of Proposal. Manufacturers must use information gathered
from the IUVP, as well as other sources of in-use emissions data, to
periodically review whether the durability procedure it employs
achieves the durability objective. EPA may require a manufacturer to
perform an analysis to evaluate its durability procedure. EPA may
withdraw approval of a durability procedure, or require modifications
to the procedure, if the Agency determines that the durability
objective is not being achieved by the durability procedure. [Ref.
86.1823-08 (i) and (j)]
    Summary of Comments. The Alliance and AIAM stated that they had
concerns that a number of variables could affect IUVP emission data
(including in-use fuel characteristics, mal-maintenance, testing
variability, small sample size, random recruitment and as-received
testing (rather than testing properly maintained and used vehicles))
and that these variables could affect the accuracy of decisions made
using IUVP data. They stated that these concerns ``were already
addressed in the CAP 2000 rulemaking in an appropriate fashion''.
    To illustrate their concern, the Alliance and AIAM provided this
example: All in-use vehicles can be well below the applicable
standards, but the durability procedure could be deemed deficient under
the proposed rule merely because in-use emissions exceed the emission
levels projected at certification.
    The Alliance and AIAM also suggested that ``If the IUVP data show
that a manufacturer meets emissions standards in use (because, for
example, the manufacturer certified with a sufficient compliance
margin, known as ``headroom''), then the Agency should not be concerned
and should not make decisions based on the accuracy of the
certification emission deterioration seen in isolation.''
    In response to a request by EPA to clarify their comments, the
Alliance stated that the new provision could be interpreted to require
changes in their durability programs even when a significant majority
of candidate in-use vehicles comply with emission standards. They
believed that the proposed rule could, therefore, effectively tighten
the applicable emission standards.
    Ford commented that: (1) The proposal effectively increases the
stringency of the standards. (2) The focus of this criteria appear to
change from the strawman which compared the IUVP emission results to
the standard and the highest certification level of all certification
and running change tests. (3) Applying the 90 percent criteria
[significant majority] criteria to IUVP data (``as received vehicles'')
rather than ``properly maintained and used'' vehicles [the quality of
data used to order recalls] further increase the stringency. (4) The
proposed requirement forces change and cost increases to methods where
100% of the IUVP data meet applicable standards. (5) Reviewing the rate
of deterioration is inconsistent with the use of certifying with aged
components (rather than calculating a deterioration factor).
    The Alliance and AIAM also commented Review of durability processes
should only be required when the in-use confirmatory test criteria are
triggered.
    Response to Comments. EPA did not propose, nor are we finalizing,
any changes to the IUVP testing program promulgated in the CAP 2000
rulemaking. As discussed in the proposal, EPA does not believe these
provisions were vacated by the Court's decision and they remain
effective without any further action required by the Agency.
    The provisions for using IUVP emissions data and/or other
information to evaluate a durability procedure and for the
Administrator to reject the use of a durability procedure based on such
an evaluation were also contained in the CAP 2000 rules. The CAP 2000
rule established the requirement to reject a

durability procedure when ``the durability process has not been shown
to effectively predict emission levels or compliance with the standards
in use on candidate vehicles'' using this data. This requirement is
practically equivalent to the ``not achieving the durability
objective'' language in the proposal. As long as in-use vehicle data is
below the standards, the durability procedure would be considered
acceptable, even if the in-use emissions exceed the emission levels
projected at certification. However, if it was found that the in-use
emissions were significantly higher than the projected certification
levels, we may decide to review the durability procedure to determine
why the in-use emission results are so far off from the projected
certification results in order to improve the procedure being used.
    We disagree with the comment that the comparison of IUVP emission
data to the durability objective in the proposal is a new requirement
(not contained in the CAP 2000 rules) that increases the stringency of
the standards. As discussed in the last paragraph, the basis for the
evaluation of a durability program in CAP 2000 was ``candidate in-use
vehicle'' which are defined to be vehicles eligible for selection by
the IUVP program. Clearly, comparing actual IUVP emission data to the
durability objective is precisely what was intended by this
requirement. Consequently, this requirement is not new and therefore
does not increase stringency of the standards. Ford is confusing the
``well maintained and used'' quality of data requirement that applies
to ordered recalls with the process of evaluating the effectiveness of
a durability process for certification. As discussed in the CAP 2000
rule, EPA does not intend to order recalls of vehicles using unscreened
IUVP data. EPA did not propose, nor are we finalizing, any provision
that would change the process of ordering recalls of non-complying
vehicles by using unscreened IUVP data.
    We continue to believe it is necessary to re-evaluate a
manufacturer's durability process using actual in-use emission, data
such as IUVP data, when that information becomes available. It is only
through such review that we can be assured that the predictions made at
the time of certification are actually valid in use. When that data
indicate that the durability process does not achieve the durability
objective in actual use, then the Agency may decide to withdraw
approval for the durability procedure or require modification to the
procedure for future certification purposes. Again, such remedial
action is necessary for the Agency to assure an effective certification
program. It would be reckless for the Agency to allow the continued use
of a unmodified durability process for future certification once it has
been shown to be ineffective in actual use for similar vehicles.
    We disagree with the suggestion that review of the durability
procedures should only occur when the in use confirmatory program
(IUCP) triggers \22\ are activated. The confirmatory test criteria are
considered to be a screening criteria that identifies the very worst
cases only for automatic reconsideration. EPA expects that there will
be cases where the durability procedures are not working satisfactorily
for a particular test group that are not identified by these criteria.
Furthermore, reviewing in-use data in large groups allows the Agency to
determine if there is an underlying trend that a durability process is
not satisfactorily achieving the durability objective. In those cases,
EPA is naturally and justifiably concerned about the accuracy of the
durability process. These reviews conducted on a case-by-case basis are
necessary for the Agency to assure an effective certification program.
---------------------------------------------------------------------------

    \22\ Mean In-Use Verification Program (IUVP) emissions for a
test group exceed threshold of 1.3 times the certification emission
standard and at least 50% of test vehicles for that test group fail
for the same pollutant.
---------------------------------------------------------------------------

    EPA has retained the proposed provision to eliminate
unrepresentative in-use data when making this determination.
    EPA has not established a single required method to perform an
analysis to evaluate the effectiveness of the durability process using
in-use emission data. The Agency will consider all information and
analyses presented by the manufacturer submitted within the 60-day
period specified in the regulations before reaching a final decision to
withdraw approval for a durability procedure. Although there is no
specified procedure for this evaluation, there are several observations
which are applicable to this process.
    Calculating deterioration rates only from in-use emission results
conducted at various vehicle mileage points on randomly procured
vehicles within a test group can be misleading. It is well known that
individual vehicle configurations within a test group or durability
group will have different levels of absolute emissions. Since the IUVP
uses random procurement, it is possible that the lower emission
vehicles would be tested at low mileage and the higher emission
vehicles would be tested at high mileage. This situation would lead to
a exaggeratedly high calculated deterioration rate. This, in turn,
could lead to the false determination that the durability process does
not meet the durability objective. Comparing individual in-use emission
levels to the certification levels or the applicable emission standards
will result in more accurate evaluations of the in-use data and is
recommended for that reason.
    It is better to make overall decisions about the effectiveness of a
durability procedure using the largest possible data set of comparable
vehicles. Consequently, EPA recommends performing analyses on a broad
group of comparable vehicles rather than on single test groups or other
small data sets. Comparable vehicles complying with different standards
may be combined into the same analysis if the emission levels are
standardized by the ratio of the emission standards.
    We agree with the Alliance and AIAM that the Agency should not make
decisions based on the accuracy of the certification emission
deterioration seen in isolation. Compliance margin should also be
considered in the analysis.
    The proposed and finalized rules discuss ``effectively representing
a significant majority'' (emphasis added). The word ``effectively'' in
this context is intended to allow the use of compliance margin (also
called ``headroom'') to expand the predictive coverage of a durability
program. As stated previously, 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 full useful life.
    This purpose may be accomplished by employing a durability process
that directly predicts emission levels that represent a significant
majority of the distribution of emission levels in actual use.
Alternatively, the durability process may under-predict emission
levels, but when coupled with the compliance margin, a significant
majority of the vehicles comply with the emission standards in actual
use. Providing that the same amount of compliance margin is used in
future certification requests, it is reasonable to conclude that such a
durability process when coupled with this level of compliance margin
effectively represents a significant majority of the distribution of
emission levels in actual use.
    For example: if after removing unrepresentative data only 70
percent of

the emission data was less than or equal to the predicted value (the
certification level determined at certification time), then one could
conclude that the predictive accuracy of the durability process was
approximately 70% which would not constitute a ``significant
majority''. If, however, when compliance margin is taken into account,
95% of the vehicles comply with the applicable emission standards, it
could be safely concluded that a significant majority of vehicles are
effectively represented by the durability procedure. Such an analysis
would be performed separately for each applicable emission constituent
and associated emission standard.
    Based on the preceding description of how the ``effectively
represent'' criteria may be implemented, we disagree with the Alliance,
AIAM, and Ford that the proposed requirements will result in the Agency
withdrawing approving for a durability process when all the IUVP data
is complying with the applicable standards.
    Lastly, we do not see an inconsistency, as a comment suggests, in
comparing IUVP emission data to the durability objective when the
manufacturer elects to certify using aged components rather than
calculate a deterioration factor. EPA is allowing flexibility in the
method for the manufacturer to conduct this analysis. EPA does not
require (nor do we recommend, as discussed above) comparing
certification DFs to DFs calculated from IUVP data. EPA's preferred
method for the analysis involves comparing IUVP emission results to
certification levels and standards; all of this data is available to
manufacturers electing to certify with aged components rather than
calculating a certification DF.
    In summary, the Agency is retaining the proposed requirement to
require manufacturers to evaluate the durability procedures using in-
use emission data generated on candidate vehicles (such as IUVP data)
and the authority for EPA to withdraw approval of the durability
procedure if the durability objective was not achieved in actual use on
comparable vehicles. The Agency did not propose, nor are we finalizing,
a specific required method to evaluate certification durability
procedures based on in-use emissions data. However, a demonstration
that approximately 90 percent of the distribution of in-use emission
results (considering each emission constituent separately) comply with
the applicable standard will be a satisfactory showing that the
durability objective has been achieved.

C. Standard Whole Vehicle Durability Procedure

1. Standard Road Cycle (SRC)
    Summary of Proposal. The standard whole vehicle durability
procedure consists of mileage accumulation on a durability vehicle
following the standard road cycle (SRC). The SRC was defined in the
proposal in Appendix V of part 86.
    Summary of Comments. The Alliance and AIAM commented that the
proposed standard road cycle is effective at meeting the Agency's
intent.
    Response to Comments. Having received no adverse comments on the
proposal, EPA is finalizing the SRC as proposed.
2. Vehicle Ballasting on SRC Mileage Accumulation
    Summary of Proposal. The proposed rules required that during
mileage accumulation ``the durability data vehicle (DDV) must be
ballasted to a minimum of the loaded vehicle weight for light-duty
vehicles and a minimum of the ALVW for all other vehicles'' [Ref
86.1823-08(c)(1)(iii)].
    Summary of Comments. The Alliance and AIAM suggested that EPA
should harmonize the vehicle weight requirements for truck DDVs with
the current emission testing requirements for emission data vehicles
(EDV).
    Response to Comments. The proposal required heavier payload for
truck mileage accumulation because trucks are designed to carry loads
in addition to transporting the occupants of the vehicle. In our review
of manufacturer vehicle design and durability processes, we found that
trucks have special design and durability requirements acknowledging
their load carrying capability. We also believe that trucks carry loads
in actual use some fraction of the time.
    The standard whole vehicle durability program is designed to
achieve the durability objective. The durability objective requires the
durability program to represent a significant majority of the
distribution of emission levels and deterioration experienced in actual
use on those vehicles. To reach this goal of significant majority
coverage, EPA believes that it is necessary to address heavier vehicle
loads that occur in trucks some fraction of the time. The adjusted
loaded vehicle weight (ALVW) loading requirement requires ballasting
with half the payload rather than 300 pounds (the loaded vehicle weight
which is applicable to light duty vehicle mileage accumulation in the
proposal).
    The amount of ballasting for mileage accumulation should not be
confused with the vehicle weight basis for conducting emission testing.
EPA did not propose, nor are we finalizing, any change to the weight
basis for emission testing, including testing that may be performed on
the DDV to calculate a deterioration factor (DF).
    Although EPA continues to believe it is necessary to ballast most
trucks to ALVW to assure that the durability objective is achieved,
this requirement may to too severe for some light light-duty
trucks.\23\ These lighter trucks are much more frequently used only for
passenger transportation and more rarely used to transport significant
payloads. Consequently, EPA is changing this provision in the final
rule to require ballasting during mileage accumulation to a minimum of
the loaded vehicle weight to apply to both light-duty vehicles and
light light-duty trucks. We are retaining the provision to ballast all
other vehicles to a minimum of the ALVW.
---------------------------------------------------------------------------

    \23\ Light light-duty trucks are trucks that are rated through
6000 pounds GVWR. This includes truck classes LDT1 and LDT2.
---------------------------------------------------------------------------

3. Calculating the DF From Mileage Accumulation of 75% of Full Useful
Life Mileage
    Summary of Proposal. The description of the proposed standard
whole-vehicle durability procedure contained a provision [Ref. 86.1823-
08(c)(2)] that would require mileage accumulation of at least 75% of
the full useful life mileage. If the mileage accumulation was less than
100% of the useful life mileage this provision would require the DF to
be based on the upper 80 percent statistical confidence limit
calculated from the emission data.
    Summary of Comments. The Alliance and AIAM commented that
projecting a full-useful life DF from data generated over 75% percent
of the useful life is sufficient without adding the proposed 80%
confidence factor. The proposed requirement is more stringent than the
original CAP 2000 and Tier 1 requirement for projecting DFs. Projected
full useful life emissions should use mean values rather than 80%
statistical point.
    Response to Comments. We disagree. EPA promulgated the provision to
allow reduced (75% rather than 100% useful life) mileage accumulation
in the CAP 2000 and Tier 1 rules to address the concern of the
excessive time necessary to complete full mileage accumulation with the
AMA cycle. The excessive time concern has been addressed in the
proposal by the SRC which is a

substantially faster \24\ cycle than the AMA cycle. For that reason,
EPA had considered eliminating the provision to allow less than full
useful life mileage accumulation altogether. Although the provision has
been rarely used in the past, EPA thought it would be worthwhile to
retain it in the standard whole-vehicle durability procedure providing
that the reduced mileage accumulation did not adversely affect the
quality of the projected DF.
---------------------------------------------------------------------------

    \24\ The fastest allowable AMA cycle (with a top speed of 70
MPH) has an average speed of 30.72 MPH while the SRC has an average
speed of 46.26 MPH. The time necessary to complete 120,000 miles on
the SRC [2594 run-hours] is less than time necessary on the AMA to
complete 75% of the miles [90,000 miles take 2930 run-hours].
---------------------------------------------------------------------------

    It is a basic statistical principle to apply a confidence factor
when performing projections from a limited data set. The confidence
factor addresses the added uncertainty inherent in not generating
actual data for the last 25% of the mileage accumulation. The one-sided
80 percent limit is a loose requirement; it is not uncommon in
projections to apply a confidence factor of 90% or higher. Running less
than the full useful life mileage accumulation is voluntary.
    The need for this confidence factor is heightened now that Tier 2
has extended useful life to a maximum of 150K miles. The idea of
allowing the 150,000 mile useful life as an option in Tier 2 [and
thereby avoiding compliance with the intermediate useful life
standards] is predicated on the assumption that the added emission data
between 120,000 and 150,000 miles would improve our statistical
confidence that the vehicles comply with full useful life standards. If
we now (as suggested in this comment) allow manufacturers to project
emission compliance without considering statistical confidence when
only 75% of useful life mileage is run, then 150,000 durability could
be demonstrated by running only 112,500 miles. Running 75 percent of
the 150,000 miles [112,500 miles] is actually less breadth of data than
the normal 120,000 miles and reduces our compliance confidence rather
than enhancing it.
    Consequently, for the reasons discussed above, EPA is adopting its
proposal to require the use of the upper 80 percent one-sided
statistical confidence limit when less than full mileage accumulation
is conducted using the standard whole-vehicle durability procedure.
4. Testing Required for DF Calculation
    Summary of Proposal. If a manufacturer elects to calculate a DF,
then it must conduct at least one FTP emission test at each of five
different mileage points selected using good engineering judgement. The
required testing must include testing at 5,000 miles and the highest
mileage point run during mileage accumulation. Additional testing may
be conducted. [Ref. 40 CFR 86.1823-08(c)(3)]
    Summary of Comments. Manufacturers should be allowed to choose the
number of tests for DF testing on the SRC, rather than the Agency
mandating the use of five (or more) tests at different mileage points
as proposed.
    Response to Comments. The reason for specifying a minimum number
and distribution of test points to be used in calculating a
deterioration factor is to assure a minimum level of confidence in the
result of the calculation. It is possible that the same level of
confidence could be achieved with multiple tests conducted at a fewer
number of discrete mileage points.
    Since the intention of this requirement was to provide a minimum
level of confidence in the DF, another plan that results in at least as
much confidence would equally achieve this goal. To allow greater
flexibility in deterioration testing plans, we are adding a provision
in the final rule that would allow other testing plans providing the
manufacturer determines, using good engineering judgement, that the
alternative plan would result in equivalent or superior DF confidence
interval.
    To justify such an alternative testing plan, the manufacturer would
need to document that the alternative testing intervals result in a DF
confidence interval equal to or better than the confidence interval
using the testing plan specified in the regulations [one test at 5,000
miles, one test at full useful life mileage, and three equally spaced
tests between 5,000 miles and the full useful life mileage].
5. Use of an Engine Dynamometer To Recreate the Aging on the SRC
    Summary of Proposal. The proposal did not specifically address what
type of dynamometer could be used for mileage accumulation on the SRC.
The proposed regulation simply specified use of a mileage accumulation
dynamometer.
    Summary of Comments. Cummins commented that vehicle mileage
accumulation on the SRC could be effectively duplicated on an engine
dynamometer by aging the complete engine and emission control system in
an appropriate manner. They suggested that EPA allow the use of an
engine dynamometer as an option for whole vehicle aging.
    Response to Comments. EPA agrees with Cummins that it is possible
to replicate the aging that occurs on the SRC by installing a complete
engine and emission control system on an engine dynamometer and
appropriately controlling the engine load and other parameters during
service accumulation. Although, this option was not prohibited in the
proposal, EPA decided to clarify the language and specifically allow
service accumulation on a engine dynamometer as an option method to
conduct aging following the SRC.

D. Standard Bench Aging Procedure

    Summary of Proposal. The standard bench aging procedure requires
installation of the catalyst-plus-oxygen-sensor system on a catalyst
aging bench. Aging on the bench is conducted by following the standard
bench cycle (SBC) for the period of time calculated from the bench
aging time (BAT) equation. The BAT equation requires, as input,
catalyst time-at-temperature data measured on the SRC. This procedure
was not applicable to diesel vehicles.
    Summary of Comments. The Alliance and AIAM commented that they
believe that the standard bench cycle incorporates appropriate elements
to provide an effective procedure to bench age exhaust emission
hardware.
    Volkswagen commented that the proposed prohibition of bench aging
procedure for use on diesel vehicles is inappropriate. The Agency
should allow manufacturers the opportunity to propose an appropriate
bench aging procedure for diesel vehicles which EPA would approve on a
case-by-case basis.
    Cummins acknowledged that there is not an effective established
procedure currently available for bench aging of diesel vehicles.
However, they encouraged the Agency to provide some mechanism in the
final rule that could allow approval of a bench aging procedure for
diesels on a case-by-case basis at a later time without the need for
further rulemaking.
    Response to Comments. Volkswagen's and Cummins suggestion that EPA
allow a manufacturer to propose a bench aging durability procedure
applicable to diesel vehicles without the Agency promulgating any
description of the framework of the bench aging durability procedure
for diesel vehicles in the regulations do not fulfill the Court's
mandate. Nor does it fulfill the Clean Air Act requirement to establish
methods and procedures for making

tests through regulation [Ref. CAA section 206 (d)].
    None of the comments take issue with EPA's conclusion that the
proposed bench aging procedures cannot be effectively used for diesel-
fueled vehicles. The proposed bench aging procedures are designed to
age the vehicle's catalyst-oxygen-sensor system as well as to replicate
the total aging that occurs in use. Diesel vehicles to not employ
catalyst technology as the principle emission control strategy,
consequently the proposed bench aging procedure will not be effective
for diesels. The comments did not suggest a bench aging procedure that
was effective for diesel vehicles. In fact, Cummins acknowledged that
there is not an effective established procedure currently available for
bench aging of diesel vehicles.
    Consequently, EPA is retaining the proposed exclusion of diesel-
fueled vehicles from employing the bench aging procedures finalized in
these regulations. 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
whole vehicle exhaust durability provisions.

E. Catalyst Time-at-Temperature Data Measurement

    Summary of Proposal. EPA proposed that catalyst temperature must be
measured at the highest temperature location in the hottest catalyst on
the DDV. Catalyst temperature must be measured at a rate of one hertz
(one measurement per second).
    Summary of Comments. The Alliance and AIAM commented that the
measurement rate of catalyst temperature of 1 hertz should be changed
to allow manufacturers to determine the appropriate rate. EPA should
not dictate the location of catalyst temperature measurements.
Determining the worst-case location is not practical.
    Response to Comments. Both of these measurement procedures only
apply to the standard bench procedure and its elements. Manufacturers
may use other procedures if using a customized/alternative process that
does not use the EPA standard BAT equation, the standard aging bench
design (as discussed in Appendix VIII) or EPA's standard method to
experimentally determine a customized R-factor for the BAT equation (as
discussed in Appendix IX).
    Because the measured temperature is the basis for calculating aging
time or determining that the appropriate amount of aging has actually
occurred on the aging bench, it is important to carefully specify where
to measure the temperature. Temperatures can vary by over 100 [deg]C
between various locations in a catalyst. In developing the BAT
equation, EPA developed the equation based on measuring the maximum
temperature in the catalyst. EPA has been receiving catalyst
temperature data from manufacturers for many years which was measured
at the hottest point in the catalyst to support carryover requests or
to evaluate durability procedure approvals under RDP-I or CAP 2000.
Typically, manufacturers have selected measure along the central axis
of the catalyst about one inch back of the front face. This history
indicates to the Agency that determination of the hottest location in
the catalyst is practical.
    In Appendix VIII, EPA proposes that the measurement of catalyst
temperature may be either at the highest temperature location or
another location (providing the temperature is adjusted by a linear
transform to represent the temperature measured at the hottest catalyst
location). To address the practicality of actual measurement, EPA has
modified the regulation language to correspond to the appendix.
    The temperature measured in a catalyst also can change quickly over
time during the SBC. When EPA was developing the standard bench cycle
we used time-at-temperature data recorded at a one hertz rate. The
temperature measured in adjacent seconds frequently is different in
these data sets. Consequently, EPA concluded that one hertz was the
minimum acceptable frequency rate acceptable for this purpose. Faster
measurement would be acceptable, because it would allow for more
accurate measurement of the changing catalyst temperature. To allow
faster measurement, EPA has changed the regulation from the proposal to
specify that one hertz is a minimum frequency.

F. Customized/Alternative Durability Procedures

    Summary of Proposal. Several of the comments received to the
proposal discuss provisions that apply to different aspects of the
customized/alternative durability procedures. As background for the
discussion of these general comments, the following paragraphs
summarize the provisions that were proposed for customized/alternative
road cycles, calculation and use the equivalency factor, and
customized/alternative bench aging durability procedures.
    Customized/Alternative Road Cycles. The Agency proposed that a
customized or alternative road cycle could be used for certification if
approved by the Administrator. The approval criteria require that the
manufacturer demonstrate that whole vehicle mileage accumulation on the
alternative/customized road cycle is expected to achieve the durability
objective in actual use for the full range of vehicles to be covered by
the procedure.
    The equivalency factor. The manufacturer must calculate an
equivalency factor that equates the alternative or customized road
cycle to the SRC run for full useful life mileage. The equivalency
factor is used to determine how much in-use data the manufacturer must
present in the analysis that the durability objective is expected to be
achieved. The equivalency factor would also be made available to
outside parties for their use to recreate aging conducted by the
manufacturer during certification. For example, if the equivalency
factor is 90% then the durability aging conducted by the manufacturer
can be replicated by running the SRC for 90% of the useful life mileage
or by bench aging using the SBC for the time calculated from the BAT
equation using time-at-temperature data run on the SRC based on 90% of
the useful life mileage.
    Customized/Alternative Bench Aging Durability Procedures. The
Agency proposed that a customized or alternative bench aging procedure
could be used for certification if approved by the Administrator. The
proposal discussed seven types of customization allowable for the bench
aging procedures and presented the criteria for their approval to the
Agency. Specifically the Agency could approve the following
customization to the standard bench aging durability procedure:
     Use a different lower-control temperature on the SBC
providing the BAT equation was used to calculate the appropriate aging
time.
     Use an customized R-factor in EPA's BAT equation providing
that it is determined experimentally using the manufacturer's actual
catalyst design.
     Use an customized A-factor in EPA's BAT equation, to
ensure that the modified durability process will achieve the durability
objective.
     Conduct bench aging using fuel with additional compounds
that may lead to catalyst poisoning, such as phosphorus, sulfur or
lead, rather than the standard fuel.
     Use an approved customized/alternative road cycle (rather
than the

SRC) to develop catalyst temperature histograms for use in the BAT
equation.
     Use a different bench cycle than the SBC with prior EPA
approval.
     Use a different method than the standard BAT equation to
calculate bench aging time with prior EPA approval.
1. Equivalency Factors and Alternative Road Cycles
    Summary of Comments. The Alliance and AIAM commented that it is
pivotal that manufacturers be able to customize the standardized
durability procedures. They support the equivalency factor approach
because it provides the means for third parties to use the SRC to
effectively replicate the aging effects produced by any manufacturer's
durability protocols without requiring manufacturers to disclose
proprietary engineering data and analysis. The equivalency factor, as
proposed, also allows these customized/alternative procedures to be
linked to the standard procedures. They do not object to the
publication of the equivalency factors, themselves, but they comment
that release of the underlying proprietary information is not required
and is contrary to the Freedom of Information Act requirements.
    Afton (formerly known as Ethyl) commented that EPA must use
appropriate rulemaking procedures which meet the requirements of
section 307(d) of the CAA to adopt alternative road cycles rather than
using the equivalency factor and the approval process discussed in the
proposal. They acknowledge that the equivalency factor may provide a
constructive means to attempt to balance the competing objectives of
maintaining the secrecy of individualized certification test
procedures, on the one hand, and disclosing to the public the test
procedures on which the government relies to issue certification
decisions, on the other. However, they state that the equivalency
factor does not alter the Agency's obligation to promulgate alternative
test procedures by regulation and include underlying data upon which
the alternative test procedure is based. Consequently they believe that
the proposed provision to allow the Agency to approve alternative road
cycles does not meet the CAA requirements nor does it comply with the
Court's mandate in Ethyl Corp. v. EPA.
    Response to Comments. We disagree with Afton's comments that the
proposed regulations, which allow the Agency to approve alternative
road cycles, do not meet the CAA requirements and do not comply with
the Court's mandate in Ethyl Corp. v. EPA. The Court stated ``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.'' That is what we have done in
this rulemaking.
    We have established procedures that define the SRC as the standard
whole-vehicle durability process. We have also described procedures to
use a customized/alternative road cycle that is tied to a comparison of
that cycle to the SRC and a demonstration that the cycle achieves the
durability objective. In particular, the customized road cycle is the
SRC run for a different distance. The actual distance run on a
customized road cycle is the basis of the equivalency factor which EPA
does not believe is confidential business information (CBI). The Agency
plans to provide the equivalency factors to any interested party and
post a listing on its Web site for public use.
    In the case of alternative cycles (cycles which use a different
speed-versus-time trace than the SRC), we have also proposed (and are
finalizing) durability procedures using those cycles. We have proposed
procedures that specify the amount and type of data necessary for
approval of such a cycle. We have proposed procedures that specify the
approval method used by the Agency for approving the cycle. We have
proposed procedures (the equivalency factor) to equate a customized
cycle to the SRC. We have determined that the equivalency factor may be
publically released. Furthermore, we have determined that if an outside
party ran a vehicle on the SRC for the distance specified by the
equivalency factor, the resulting deterioration would be equivalent to
the manufacturer's durability showing using the customized road cycle.
We have also proposed procedures that specify how to use the customized
road cycle for calculating deterioration factors and/or conducting aged
component testing. Lastly, we have proposed procedures for determining
compliance using this data.
    In summary, in addition to the SRC, we have proposed and are
finalizing, many details on the durability procedure for the use of
customized road cycles. We believe we have clearly articulated a
durability procedure (i.e., the SRC) by regulation fulfilling the
mandate of the Court. We have also used our discretion in electing to
describe most, but not all details, of the alternative road cycle
durability process in the regulations. (See American Trucking
Associations v. Department of Transportation, 166 F.3d 374 (DC Cir.
1999) and New Mexico v. EPA, 114 F.3d 290 (DC Cir. 1997). Agencies are
entitled to broad deference in picking the suitable level of detail to
specify in the regulations.)
    For the above reasons, EPA is finalizing the provision to allow
alternative road cycles approved by the Administrator as proposed.
2. Bench Durability Aging
    Summary of Comments. Afton expresses concern that whether and how
new systems perform in the field can directly impact operation of the
catalyst in ways that may not be captured by thermal aging. They
specifically cite the lack of aging of certain engine and fuel system
components. They expressed concern that the analysis presented in EPA's
draft technical support document (TSD) for the CAP 2000 proposal, which
shows little engine-out deterioration, may be dated. Their concern is
based on the fact that the analysis does not include vehicles using
certain new technology devices and strategies which may, at some future
time, begin to appear in production but which are not used in general
production vehicles at this time.
    The Alliance and AIAM commented that the bench aging procedures
incorporate appropriate elements to provide an effective method to
bench age exhaust emission hardware.
    Response to Comments. We do not share Afton's concern that the
proposed bench aging procedures may not be sufficiently accurate for
certification purposes. The bench aging procedures are designed to
effectively replicate the aging that occurs during in-use operation.
    As discussed in the preamble to the proposed rule, the bench aging
procedures are required to be adjusted to duplicate the full emission
deterioration that occurs in-use by thermally aging the catalyst. This
may result in over-aging the catalyst to account for emission
deterioration that occurs from other sources. The amount of over-aging
may be large or small. The proposed BAT equation includes a term (the
A-factor) which is used for this purpose. EPA has set the initial value
of A as 1.1 based on the low expected engine-out deterioration
identified in the TSD. However, if for any cause (including unexpected
emission control deterioration of components not aged on the aging
bench, or based on the future technology that Afton mentions in their
comments), the bench aging durability does not achieve the durability
objective, EPA has proposed a requirement that manufacturers change

the A factor to ensure that the durability goal is appropriately
achieved by the bench aging process. Furthermore, EPA has proposed
requirements that the manufacturer must periodically review their
durability process to assure that the durability object is achieved in
actual use. To facilitate this review, EPA requires manufacturers to
provide IUVP emission data that must be used in this evaluation
process. Lastly, EPA can require the manufacturer to change their
durability process if the Administrator determines that the durability
goal is not being achieved in actual use. Consequently, any risk that
the bench aging process may not achieve the durability goal is
controlled by this feedback process using IUVP emission data.
    For the above reasons, EPA is finalizing the standard bench aging
durability procedures as proposed.
3. Approval of Customized/Alternative Durability Procedures
    Summary of Comments. The Alliance and AIAM made a series of
comments to ``eliminate unnecessary and excessive administrative
burden''. Specifically they suggested:
    Manufacturers should be allowed to self-approve a customized/
alternative durability road cycle if they can show it is more severe
than the SRC.
    Manufacturers should not be required to submit data from 20 in-use
vehicles to obtain approval, rather the manufacturer should review in-
use data as it becomes available.
    The proposal requires the approval of a customized bench aging
cycle even when the aging time is determined using the BAT equation.
They suggest that this additional approval step is unnecessary and
unjustified.
    EPA should eliminate all requirements for pre-approval and re-
authorization of existing durability protocols absent in-use data which
does not meet the existing requirements.
    Response to Comments. We disagree that the approval requirements of
the proposal are either unnecessary or excessively burdensome. EPA must
determine to its satisfaction that a potential customized/alternative
durability process is expected to achieve the durability goal in use.
Most of the durability procedures approved prior to the vacature of CAP
2000 rules were significantly changed based on the Agency's review and
comment during the Agency's initial review. Although we now expect that
most manufacturers have the skill necessary to design an appropriate
customized/alternative process, we still believe that an initial review
and approval by the Agency is still warranted.
    The proposal only requires an initial approval of the customized/
alternative durability process. Once a process is approved, the
manufacturer must determine, using good engineering judgement, whether
to apply the procedure to future durability groups.
    The proposal does contain provisions to require less in-use data
for EPA approval when the customized/alternative cycle is shown to be
significantly more severe than the SRC. We expect that approval of more
severe cycles than the SRC to be granted, but the question still
remains whether the customized/alternative cycle is severe enough to
achieve the durability objective in use for the vehicles involved.
Consequently, approval of a more severe customized/alternative cycle is
not automatic.
    In the proposal, the amount of in-use emission data required for
approval is varied depending whether the cycle is more or less severe
than or approximately equivalent to the SRC. The amount of data
required reflects the data necessary for the Agency to reach a valid
conclusion to approve a cycle. As previously discussed, more severe
cycles are rewarded in the approval process by a reduction in the
amount of required data.
    The proposal requires approval of an alternative bench aging cycle
because the distribution of air/fuel ratios and temperature is
important to assure that adequate aging occurs. As discussed in the
preamble to the proposed rule, a manufacturer must develop a new R
factor if they change the bench aging cycle. Our standard R-factor
applies only to the standard bench cycle (SBC). The determination of a
customized R-factor is necessary because the same temperature exposure
will result in a different amount of emission deterioration if the
bench aging cycle is changed. The use of the standard BAT equation
[with a different R-factor] provides no added assurance that the bench
aging cycle will effectively replicate the emission deterioration that
occurs on the associated road cycle as suggested in the comment.
Consequently, EPA is finalizing the requirement to obtain Agency
approval for alternative bench cycles.
    The proposed requirements are different than the CAP 2000
requirements, although the durability objective has not changed.
Pertinent facts may have changed since the approval (under the CAP 2000
rules) of a particular durability procedure including production
designs and the existence of more in-use data available for review.
Although, the Agency expects that most of the durability processes that
were approved prior to the court's vacature of the CAP 2000 rules will
meet the requirements of this rule, we find no compelling case to make
any blanket determination. Reviewing each durability process according
to the new requirements on its own merits is an appropriate course of
action for the Agency. Therefore, EPA is retaining and finalizing the
proposed requirement that all customized/alternative durability
procedures must be approved under the new rules (including all
procedures used before the vacature of the CAP 2000 rules).
4. Experimentally Determining a Customized R-Factor
    Summary of the Proposal. EPA proposed that a manufacturer may
determine an customized R-factor for use in the BAT equation. This
would allow the BAT equation to be customized to better predict the
required amount of bench aging necessary for a particular catalyst
design. EPA proposed a standard experimental method for determining a
customized R-factor in Appendix IX to the rule. EPA also proposed that
other experimental techniques may be used if approved by the
Administrator. To obtain approval the manufacturer must demonstrate
that the calculated bench aging results in the same (or larger) amount
of emission deterioration as the associated approved road cycle.
    Summary of Comments. The Alliance and AIAM commented that EPA's
standard method for experimentally determining a R-factor [in Appendix
IX] is overly restrictive and significantly increases the stringency of
determining an R-factor.
    Ford commented that the approval procedure for using alternative
techniques to experimentally determine the R-factor for the BAT
equation should be based on accomplishing the durability objective
rather than a comparison to the associated road cycle (the criteria in
the proposal).
    Ford suggested an alternative standardized method to experimentally
determine the R-factor that they felt would be more accurate and easier
to implement. Their proposal (a detailed description is in the docket)
suggested that emissions rather than catalyst efficiency be measured
and that the emission deterioration projected from a least-squares
regression of the emission versus time data be calculated directly from
the experimental data rather than the two step process proposed by EPA.
    Response to Comments. EPA agrees that the standard method for

experimentally determining an R-factor supplied by Ford in their
comments would be appropriate to use for that purpose. We also
anticipate that it would be easier to generate the emission data
required in Ford's alternative procedure than the conversion efficiency
required in the proposed standard R-Factor determination procedure.
Also this alternative approach eliminates one step compared to the
proposed process. For those reasons, we have modified the Appendix in
the final rule to allow this procedure.
    It should also be noted that other techniques, beyond the standard
procedure outlined in Appendix IX to part 86, may be used as allowed in
40 CFR 1823-08(e)(2)(iii). Ford recommended that we take a step back
from the proposed approval criteria which require ``that the calculated
bench aging time results in the same (or larger) amount of emission
deterioration as the associated approved road cycle.'' They recommended
that we require instead that the manufacturer should demonstrate that
the use of the R-factor would achieve the durability objective. One
concern was that the proposed text seemed to require the existence of a
customized/alternative road cycle because this would be the only cycle
that was ``approved'', the SRC could be used without a specific Agency
approval.
    It was not our intention to require that a manufacturer have an
approved customized/alternative road cycle to determine an R-factor by
an alternative method (rather than the standard method in Appendix IX
to Part 86). Manufacturer may also use an alternative method to
calculate an R-Factor when using the SRC as the associated road cycle
to measure catalyst time-at-temperature data necessary to calculate
aging time. It is our intention however, that a manufacturer must
generate catalyst time-at-temperature data on either the SRC or an
approved customized/alternative road cycle. Furthermore, that an
alternative method will only be approved if it results in the same (or
more) aging as that associated cycle.
    We believe that the approval criteria suggested by Ford (achieving
the durability objective) will be functionally the same as the proposed
criteria to replicate the aging seen on the associated road cycle but
potentially less burdensome. For an alternative bench cycle to be
approved the manufacturer must demonstrate that it achieves the
durability objective. However, in the case where a manufacturer is
using the SRC, it may not have the necessary in-use emission data to
demonstrate that durability objective is being achieved. For these
reasons, we continue to believe that the proposed requirement is a less
burdensome and equally effective requirement as Ford's proposal. In
today's final regulation text we have clarified that the road cycle
used for comparison may be either the SRC or an approved customized/
alternative cycle. Otherwise, we have finalized the alternative R-
factor methodology approval criteria as proposed.
5. Alternative Bench Aging Cycle Content
    Summary of Proposal. EPA did not propose any limitations on the
content of an alternative bench aging cycle. EPA did propose that to
obtain approval for such an alternative bench cycle the manufacturer
must demonstrate that bench aging with the new bench cycle provides the
same or larger amount of emission deterioration as the associated road
cycle.
    Summary of Comments. The Alliance suggested that we clarify which
provisions (in the proposed section 86.1823-08(e)(2)) pertain to
manufacturers bench cycle and which provisions pertain to the EPA
standard bench cycle.
    Response to Comments. EPA did not propose, nor are we finalizing,
any limitations on the content of an alternative bench aging cycle. The
alternative cycle may (among other differences) be of different length,
have a different proportion of Air/Fuel ratios, different temperatures,
different amounts of secondary air injection, and/or use no secondary
air injection at all. However, whatever the content, the manufacturer
must demonstrate that the alternative bench aging cycle works
effectively by reproducing (or alternatively overstating) the aging
that occurs on the associated road cycle which was used to measure the
time-at-temperature data used to calculate the aging time on the aging
bench.

G. Component Durability

    Summary of Proposal. The proposal retains the CAP 2000 requirement
that manufacturers use good engineering judgement to determine that all
exhaust-related components are designed to operate properly for the
useful life of the vehicles in actual use.
    Summary of Comments. Afton argued that EPA did not meet the
requirements of the Act or the Court's mandate in Ethyl Corp. v. EPA,
by not proposing test methods or procedures for assessing the
durability of emission control system components, either separately for
components, or for all the components operating together as an
integrated system.
    In response to this comment, the Alliance and AIAM stated that
there is no need to implement additional ``component'' durability test
methods and procedures because the SRC re-establishes the requisite
threshold level of stringency for the components as well as the system
as a whole. They also claim that the Court did not impose any
obligation on EPA to establish a whole new regime of component
durability tests.
    Response to Comments. While EPA believes that Afton has raised an
important issue, the NPRM did not contemplate any revisions to the
component durability regulations. Therefore, EPA believes that before
taking any final action on component durability, it is appropriate to
open this issue to further comment. Therefore, concurrent with today's
final rule, EPA is publishing a Supplemental Notice of Rulemaking
(SNPRM) that addresses component durability. The SNPRM will seek
comment on several options that EPA is considering for addressing
component durability during the vehicle emissions certification
process. After a formal comment period, EPA will consider any further
comments received and issue a final rule.

H. Minor Modifications to Approved Durability Procedures

    Summary of Proposal. The proposal contained a provision [ref.
86.1823 h) (1)] that allowed a manufacturer to modify an approved
durability procedure by increasing or decreasing the number of miles
run on an approved road cycle to represent full or intermediate useful
life emissions deterioration or by changing the A-Factor in the BAT
equation for a bench aging, using good engineering judgment, to ensure
that the modified procedure will achieve the durability objective.
    Summary of Comments. The Alliance and AIAM commented that EPA
should restore the CAP 2000 provision that allowed manufacturers to
make minor modifications (using good engineering judgement) to an
approved durability procedure without the need to obtain a new approval
from EPA.
    Response to Comments. The proposal listed only certain changes that
the manufacturer could make to an approved durability procedure using
good engineering judgement without obtaining approval by the
Administrator. Those changes were increasing or decreasing the number
of miles run on an approved road cycle or changing the A-Factor in the
BAT

equation. At that time, these were the only changes that the Agency
envisioned that could be applied to the standard EPA durability
procedures without considering the changes to constitute a
customization of the standard procedures that would require Agency
approval. We also proposed that these same changes could be made to
customized/alternative durability procedures without requiring Agency
approval.
    We agree that allowing some level of minor adjustments or changes
to an approved customized/alternative manufacturer durability process
would also be appropriate if the changes were limited in scope and made
using good engineering judgement to assure that the modified durability
procedures would achieve the durability objective. We believe that the
level of adjustments allowed under CAP 2000 continue to be appropriate
in the new durability regulations. In the vacated CAP 2000 durability
regulations we stated: (1) Such modifications will be limited to
incorporating additional data into the original algorithms of the
approved durability process and (2) if a manufacturer wishes to change
the algorithms used to determine the aging characteristics of the
durability process, these changes will be considered a new durability
process and will require advance approval by the Administrator.
Therefore, we have modified the final regulation language to include a
provision for manufacturers to make these minor changes, using good
engineering judgement, without obtaining new approval from the Agency.

I. Required Notification to EPA That an Approved Durability Procedure
Will Be Used for a Particular Durability Group

    Summary of Proposal. The manufacturer must notify the Administrator
of its determination to use an approved (or modified) durability
procedure on particular test groups and durability groups prior to
emission data vehicle testing for the affected test groups
(notification at an annual preview meeting scheduled before the
manufacturer begins certification activities for the model year is
preferred).
    Summary of Comments. The Alliance and AIAM commented that the
timing of the notification (prior to emission data vehicle testing) is
too early in the certification process. They suggested that
notification in the Application for Certification should be sufficient
and is preferable to them.
    Response to Comments. The purpose of this requirement is to provide
the Agency the necessary information about the manufacturers durability
demonstration plans early enough in the certification process to be
useful to the Agency. In particular, if the Agency wished to question
the manufacturers judgement to apply a durability procedure to a
particular durability group, it would be more efficient to raise this
issue earlier in the certification process. Consequently, the Agency
suggested that the notification occurs in the annual preview meeting
which is typically scheduled before a manufacturer begins certification
activity for a model year.
    As discussed in the current good engineering judgement provisions
[ref. 40 CFR 86.1851-01 which is not being modified in today's final
action] the Administrator may reject a manufacturers decision, even
after certification is granted, if it is not based on good engineering
judgement. Consequently, EPA agrees that notification at the time of
the Application for Certification would provide the opportunity for
sufficient oversight for the Agency. The risk to the manufacturer is
that any questions regarding the good engineering decision basis of the
manufacturers decision to apply a durability procedure to a certain
durability group will come late in the process (or even after
certification was granted). The good engineering judgement provisions
in the current rule provide sufficient tools for the Agency to address
these concerns in that time period. We still suggest that the best time
for the notification is at the preview meeting to avoid last minute
questions in the certification process. Nevertheless, we are changing
the final regulation language to require the notification prior to or
concurrently with the Application for Certification.

J. Public Availability of the Equivalency Factor and Supporting Data

    Summary of Proposal. EPA proposed methods to calculate the
equivalency factor. EPA also stated the opinion in the proposal that
the equivalency factor was not confidential business information (CBI)
and it may be released to the public. EPA also announced its plan to
post the equivalency factors on the Agency's Web site.
    Summary of Comments. The Alliance agreed with the proposal that the
equivalency factor is not confidential and may be released to the
public. However, they stated that manufacturers should not be compelled
to disclose to the public any of their underlying data or other
proprietary information used to develop their durability process.
    The Alliance and AIAM also commented that EPA should not require
extensive engineering reports justifying equivalency factors unless
there is in-use or other data suggesting that the manufacturer's cycle
does not achieve the durability objective.
    They also commented that manufacturers should only be required to
supply equivalency factors for processes that are used in the future
(after the effective date of the proposed rules).
    Afton commented that the Court's mandate Ethyl Corp. v. EPA,
applies to all certification decisions made since the effective date of
the mandate. Specifically, they disagreed with the Alliance and AIAM
comment that equivalency factor need only be supplied for new
durability procedures approved under the proposed rules and need not be
reported for existing durability processes that were used after the
vacature of the CAP 2000 rules as well as aging processes that were
approved by EPA prior to the vacature.
    Response to Comments. EPA continues to believe that the equivalency
factor is not confidential business information and may be released to
the public. EPA renews its intention to post the equivalency factors on
the Agency's Web site for public use.
    We are not making any other determinations (beyond the equivalency
factor) regarding whether other information submitted by a manufacturer
is or is not confidential business information. These decisions to
release other information will be made on a case-by-case basis using
the existing regulations [Ref. 40 CFR part 2].
    We agree with Afton that the Court's mandate applies to all
certification decisions made after the effective date of the mandate.
However, once the Court's mandate became effective, EPA ceased
requiring durability showings as a prerequisite to issuing a
certificate of conformity. The basis for granting certification after
the vacature of the CAP 2000 rule was EPA reliance on a statement made
by the manufacturer using good engineering judgement that the vehicles
in question will comply with the applicable standards for their full
useful life. This statement was typically placed in the Application for
Certification and has not generally been viewed by manufacturers as
confidential business information. There are no approved durability
procedures between the effective date of the Court's mandate and the
effective date and model year of today's final rules. Consequently,
there are no equivalency factors nor any supporting data that can be
made

available by the manufacturers that apply to certification during that
period.

K. Carryover

    Summary of Proposal. EPA did not propose any changes to the
carryover provisions in the current regulations (ref. 40 CFR 86.1839-
01). These provisions allow manufacturers to use durability data that
was previously generated and used to support certification provided
that the data ``represent a worst case or equivalent rate of
deterioration''.
    EPA proposed that the manufacturer may not, however, continue to
use CAP 2000 durability processes to generate new data starting with
the effective date of the new regulations. When the proposed rule
becomes effective, manufacturers must use durability procedures that
have been approved under the new rules to generate new durability
demonstrations.
    Summary of Comments. The Alliance and AIAM commented that, in
addition to allowing carry over of existing durability data prior to
CAP 2000 vacature, manufacturers should also be allowed to use existing
durability data employed after vacature from previously approved
processes conforming with good engineering judgment.
    They also suggested that manufacturers should be allowed to carry
over aging data generated after the vacature of the CAP 2000 rules
providing that these data were compiled using aged component processes
approved by EPA prior to the vacature.
    Lastly, they commented that manufacturers should be allowed to
continue to use aging processes approved by EPA prior to the vacature
to age components on future data fleet vehicles.
    Response to Comments. EPA did not propose any change to the
carryover provisions. After the effective date of the new regulations,
if a manufacturer can meet these requirements, it may use existing
durability data (i.e., DFs or aged hardware). This would apply to any
data that exists prior to the effective date of the today's regulation
which is compiled using a durability procedure that was approved prior
to the vacature of the CAP 2000 rules. All new data generated after the
effective date of today's rulemaking must meet all the applicable
requirements including the requirement that it was generated using an
approved durability procedure.

L. Evaporative Durability Procedures

    Summary of Proposal. The proposal contained provisions for
conducting evaporative durability using either a (1) whole vehicle
demonstration using the SRC or another approved road cycle or a (2)
bench aging demonstration using procedures contained in the regulations
or (3) a combination of whole vehicle and bench procedures.
    Summary of Comments. The Alliance and AIAM commented that the
Court's ruling dealt exclusively with tailpipe emissions and did not
compel EPA to revisit evaporative durability.
    They also commented that separate durability demonstration for each
evaporative family should be allowed via carryover using good
engineering judgment.
    They also commented that EPA's right to revoke use of evaporative
durability based on IUVP is not in keeping with CAP 2000, which said
that EPA would use the data primarily for modeling purposes. They are
concerned that the sample size is too small and would force
manufacturers to ensure that IUVP evaporative emission test vehicles
match the emission level of certification test vehicles. Non-fuel
related emissions can not be represented in the certification
durability process.
    Response to Comments. We disagree that the Court's decision
regarding durability was limited to exhaust emission deterioration.
Consequently, we proposed (and are finalizing) exhaust, evaporative,
and refueling durability procedures.
    As discussed previously, the carryover procedures of the current
regulations (ref. 40 CFR 86.1839-01) are not changed on the proposal.
These provisions allow manufacturers to use durability data that was
previously generated and used to support certification provided that
the data ``represent a worst case or equivalent rate of
deterioration''. Consequently, existing evaporative durability data and
results may be carried-over providing they meet these requirements.
    We agree that the IUVP sample size (one test per test group) is too
small to make this decision on an individual test group basis. However,
EPA intends to review in-use evaporative data and evaluate the
effectiveness of the durability process to achieve the durability
objective when a reasonable amount of data does exist for this purpose.
This expanded data set could include data from another source or it may
consist of data combined from several related test groups or from
several years of IUVP data. If the expanded data set indicates a
problem, EPA believes it is appropriate to invoke this provision to re-
evaluate the manufacturer's evaporative durability procedure.
Furthermore, if the Agency ultimately concludes that there is
sufficient data and that the data indicate that the durability
objective is not achieved, EPA believes it is appropriate to require
modifications to the durability procedure in the same method used for
exhaust emission deterioration. It would not be acceptable to continue
to use an evaporative durability process that was demonstrated to not
achieve the durability objective; EPA relies on the accuracy of this
data to make appropriate decisions to grant certification.
Consequently, we are finalizing these provisions as proposed with the
acknowledgment that a sufficient body of data must exist to make this
determination with appropriate confidence.

M. Starting Model Year for the Rule

    Summary of Proposal. EPA proposed that the rules would apply to
2006 model year vehicles certified after the effective date of the
regulations.
    Summary of Comments. The Alliance and AIAM commented that the
proposed effective date of 2006 model year (MY) should be changed to
2008 MY, or later if final rule published after August 2004. They
stated that manufacturers are already doing durability testing on 2006
models, and developmental work is already underway for early
introduction 2007 models.
    Volkswagen commented that the effective date of 2006 MY is
unworkable, but they do not propose an alternative date.
    Ford commented that the effective date for the regulation should be
changed to 2009 MY if component durability issues are addressed in a
single rulemaking and 2008 MY if the emission deterioration provisions
are finalized separately.
    The Alliance and AIAM suggest that we add a provision allowing
early opt-in at the manufacturer's discretion.
    Response to Comments. We agree that 2006 is no longer possible
given the current timing for publication of the final rule. Because
publication of the FRM has taken longer than expected, and
manufacturers are now certifying 2006 model year vehicles and already
performing durability testing for 2007 models, we are delaying the
implementation of the rule to become effective beginning with the 2008
MY.

N. Special Provisions for New Manufacturers

    Summary of Proposal. EPA did not propose any special procedures for
new manufacturers to obtain approval of a customized/alternative
durability procedure. However, the standard procedures may be employed
by these

manufacturers without generating any in-use emission data. Also, the
Agency did not change the special certification procedures that apply
to small volume manufacturers (ref. 40 CFR 86.1838-01).
    Summary of Comments. The Alliance and AIAM commented that new
manufacturers should not have to rely on IUVP data for feedback
purposes since they supply little or no IUVP data. They suggested that
the rule should have clear provisions for new manufacturers.
    Response to Comments. New manufacturers may use the standard
durability procedures without submitting in-use data or obtaining EPA
approval. We believe that these standard procedures provide a
reasonable method for new manufacturers to supply the required
durability data without the need to compile in-use emission data.
However, if a new manufacturer did wish to obtain approval for a
customized/alternative durability road cycle, EPA would accept
appropriate data from another manufacturer's comparable in-use vehicles
to demonstrate the effectiveness of their durability procedures to
achieve the durability objective.

O. Delete Incorrect Reference to Intermediate Useful Life Standards for
the Evaporative and Refueling Durability Objective

    Response to Comment. We made the appropriate correction in the
final regulations.

P. Comments From a Private Citizen

    Summary of Comments. One citizen submitted comments that touched
upon various topics, many of which were not germain to the proposed
rule. In general, the consumer believed that the proposal was ``too
friendly'' to manufacturers. The commenter requested that the public
should always be invited to all meetings EPA has with manufacturers to
assure that no ``secret dealings'' are taking place.
    EPA response. Some of the comments touched on issues that have been
addressed elsewhere in this section. We disagree that the proposal was
``too friendly'' to manufacturers. Emissions durability requirements
impose a significant burden on manufacturers, and the provisions to
allow for alternatives does not lessen the responsibility placed upon
manufacturers to perform the required emission durability
demonstration. We also disagree that all meetings with manufacturers
should be open to the public. The discussions at these meetings center
around individual manufacturers' business plans and are forward-looking
in nature. Revealing these plans publicly would compromise the
competitive automotive market. However, by informing the public of what
sort of information is exchanged in these meetings, we believe we have
provided the public with enough assurance that no ``deals'' are being
made.

III. What Is EPA Promulgating Today?

    Today's final rule includes two well-defined test methods for
determining the exhaust emissions durability of vehicles from which
manufacturers may choose: the standard whole vehicle aging process and
the standard bench aging process. It also includes well-defined
criteria allowing EPA to approve customization of or alternatives to
these test methods, based upon a demonstration to EPA of the level of
stringency needed to meet the durability objective, and the level of
stringency demonstrated for the SCR and the customization or
alternative.

A. Standard Whole Vehicle Exhaust Durability Procedure

    EPA is promulgating a standard road cycle (SRC) which is targeted
to effectively cover a significant majority of the distribution of
exhaust emission deterioration rates that occur on candidate in-use
vehicles. The SRC is fuel-neutral. It applies to all vehicles,
regardless of fuel used. The SRC consists of seven laps of 3.7 miles
each. The average speed on the SRC is 46.3 mph, the maximum cruise
speed is 75 mph, and the acceleration rates range from light to hard
accelerations. Most accelerations are moderate and there are no wide-
open-throttle accelerations. The SRC contains 24 fuel-cut
decelerations. The deceleration rates range from coast-down (no brake
force applied) to moderate.
    EPA is promulgating a standard whole vehicle durability procedure
which consists of running a vehicle (the durability data vehicle (DDV))
on the SRC for the full useful life mileage of the vehicle. We are also
finalizing rules that manufacturers may terminate mileage accumulation
at 75% of full useful life and project DFs based upon the upper 80%
statistical confidence limit.
    The weight of the vehicle during SRC mileage accumulation is
proposed to be the loaded vehicle weight (curb plus 300 pounds) for
light-duty vehicles and light light-duty trucks. The weight basis for
SRC mileage accumulation is the adjusted loaded vehicle weight ((curb +
gross vehicle weight)/2) for all other vehicles covered by this rule.
The fuel used on the SRC is proposed to be representative of
commercially available gasoline (with a provision that extra poisoning
may be added, such as phosphorus, sulfur or lead).
    EPA is retaining the CAP 2000 options of determining emission
compliance levels by either (1) calculating deterioration factors (DF)
and applying the DF to the emission data vehicle (EDV) emission results
or (2) testing the EDV with emission control components aged using the
SRC and installed prior to testing. If DF's are to be calculated,
emission testing would be conducted at periodic intervals during milage
accumulation.

B. Standard Bench Aging Exhaust Durability Procedure

    Bench aging is a different way to achieve the same emission
deterioration as whole-vehicle aging using a road cycle. EPA is
promulgating a standard bench aging procedure that uses a bench aging
time (BAT) equation and the standard bench cycle (SBC) to reproduce
emission deterioration from a road cycle. EPA's standard bench
procedure specifies that the SRC be used to generate the catalyst
temperature histogram needed to determine bench aging time. Because the
standard bench aging procedure relies on increasing catalyst thermal
aging to account for all sources of emission deterioration, this
procedure is not applicable to diesel fueled vehicles or vehicles which
do not use a catalyst as the principal after-treatment emission control
device.
    The standard bench aging durability procedure has been designed to
reproduce the exhaust emission deterioration that occurs on the
standard whole vehicle durability procedure. The standard bench aging
procedure is as follows:
    a. Catalyst temperature data is measured at a minimum rate of one
hertz (one measurement per second) during at least two replicates of
the standard road cycle (SRC). The temperature results are tabulated
into a histogram with temperature bins of no larger than 25 [deg]C.
    b. The effective reference temperature of the standard bench cycle
(SBC), described below, is determined for the catalyst system and the
aging bench which is to be used for the bench aging.
    c. The bench aging time is calculated using the bench aging time
(BAT) equation, described below, using the effective reference
temperature of the SBC and the catalyst temperature histogram measured
on the SRC.
    d. The exhaust system (including the catalyst and oxygen sensors)
is installed on the aging bench. The aging bench

follows the SBC for the amount of time calculated from the BAT
equation.
    e. Catalyst temperatures and A/F ratios are measured during the
bench aging process to assure that the proper amount of aging has
actually occurred. Aging on the bench is extended if the aging targets
are not properly achieved.
1. The Standard Bench Cycle (SBC)
    EPA is promulgating a standard bench cycle (SBC) which contains a
mix of rich, lean and stoichiometric A/F ratios designed to achieve
appropriate emission deterioration on the aging bench when operated for
the period of time calculated from the BAT equation.
    The standard bench cycle consists of a 60-second cycle which is
defined based on the A/F ratio of the engine (which is part of the
aging bench) and the amount of secondary air injection (shop air which
is added to the exhaust stream in front of the first catalyst).
2. The Bench-Aging Time (BAT) Calculation
    EPA is promulgating a bench aging time (BAT) equation to calculate
the appropriate length of time to age a catalyst system on an aging
bench to yield equivalent emission deterioration as running a vehicle
on the associated road cycle. The standard bench aging durability
procedure uses catalyst temperatures measured on the SRC to calculate
the bench aging time necessary to reproduce the thermal exposure seen
on the SRC. As discussed in the NPRM preamble, the BAT equation is
based on the Arrehenius equation which relates chemical reaction rates
with temperature.
3. The Effective Reference Temperature for the SBC
    The BAT equation uses a single temperature value called the
effective reference temperature to represent the entire temperature-
history experienced during the SBC on the catalyst aging bench. The
effective reference temperature will be calculated using catalyst
temperature histogram data measured in the catalyst on the aging bench
following the SBC. The BAT equation would then be used to calculate the
effective reference temperature by iterative changes to the reference
temperature (Tr) until the calculated aging time equaled the
actual time representing in the catalyst temperature histogram. The
resulting temperature is the effective reference temperature for the
SBC.

C. Customization of the Standard Procedures

1. Customization of the Standard Road Cycle
    EPA has established criteria to obtain approval for a customized/
alternative road cycle that require the manufacturer to demonstrate
that the objective of the durability program will be achieved for the
breadth of the vehicles which are covered by the cycle. Approval of a
customized/alternative road cycle requires a thorough analysis of
whether the cycle will achieve the durability program objective using
in-use emissions data, including a demonstration of the relative
stringency of the SRC and the manufacturer's program.
    To make the initial demonstration necessary for the Agency to
approve a customized/alternative cycle, EPA is requiring 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). Manufacturers could use previously generated in-use data
from the CAP 2000 high mileage IUVP program or the fourth-year-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.
    The amount of in-use emission data required for this analysis 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. However, 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 will also consider the equivalency factor of the customized/
alternative cycle when evaluating the cycle for approval.
    Once the durability process is approved, the manufacturer must
determine, using good engineering judgement, whether to apply the
durability procedure to a particular test group. The manufacturer may
make modifications to an approved customized/alternative road cycle and
apply them to a test group to ensure that the modified process will
effectively achieve the durability objective for future candidate in-
use vehicles. The manufacturer would be required to identify such
changes in its certification application and explain the basis for the
changes. 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.
2. Customization of Standard Bench Procedures
    The manufacturers are allowed, subject to Agency approval, a
limited degree of customization of the standard bench procedures.
However, in all cases EPA is requiring that alternative bench aging
procedures be based upon measured vehicle performance (such as catalyst
temperature) on an approved road cycle.
    Specifically EPA is allowing customization of any or all of the
following parameters when the accompanying conditions for approval are
met:
    a. The lower control temperature on the SBC may be modified without
prior EPA approval provided that the high control temperature is set 90
[deg]C ( 10 [deg]C) above the lower control temperature and
an approved BAT equation is used to calculate bench aging time.
    b. The R-factor used in EPA's BAT equation may be determined
experimentally using EPA's standard procedures (specified in the
appendix to the regulations) without prior EPA approval. Other
experimental techniques to calculate the R-factor require advance EPA
approval. To obtain approval, the manufacturer must demonstrate that
the calculated bench aging time results in the same (or larger) amount
of emission deterioration as the associated road cycle.
    c. The A-factor used in EPA's BAT equation may be modified, using
good engineering judgement without prior EPA approval, to ensure that
the modified durability process will achieve the durability objective
(discussed previously).

    d. Bench-aging may be conducted using fuel with additional poisons
(such as phosphorus, sulfur and lead) without prior EPA approval. Using
fuel with additional poisons is worst case for emissions deterioration.
Normally a manufacturer using fuel with additional poisons will either
calculate a new R-factor or A-factor to assure that the durability
objective is properly achieved.
    e. An approved alternative road cycle or customized SRC may be used
to develop catalyst temperature histograms for use in the BAT equation
without additional EPA approval beyond the original approval necessary
to use the road cycle for mileage accumulation.
    f. A different bench cycle may be used during bench aging with
prior EPA approval. To obtain approval the manufacturer must
demonstrate that bench aging with the new bench cycle provides the same
(or larger) amount of emission deterioration as the associated road
cycle.
    g. A different method to calculate bench aging time may be used
with prior EPA approval. To obtain approval the manufacturer must
demonstrate that bench aging for the time calculated by the alternative
method results in the same (or larger) amount of emission deterioration
as the associated road cycle.
3. Reproducibility by Outside Parties
    EPA is finalizing the provision that an alternative road cycle must
be designed to achieve the durability objective. As part of this
evaluation, EPA is requiring that all alternative road cycles are
equated to the SRC by means of an equivalency factor that determines
the amount of SRC-driving that results in the same emission
deterioration as the alternative cycle. EPA is requiring that every
alternative bench aging procedure be based upon measured vehicle
performance on an approved road cycle. Lastly, EPA is requiring that
any alternative bench cycle be designed to result in the same levels of
emission deterioration as the road cycle upon which it was based.
    An important element of the regulation is that, regardless of
whether a manufacturer uses the EPA standard procedures or customized
procedures, any interested party will be able to use the equivalency
factor to reproduce the amount of emission deterioration produced by
any manufacturer's customized/alternative durability process used
during vehicle certification. Any alternative road or bench procedure
is equated to a given number of miles on the SRC.
    To reproduce the deterioration generated by a customized/
alternative 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).

D. Using IUVP Data To Improve Durability Predictions

    Manufacturers are required to review their durability program and
prepare an analysis for EPA evaluation when: (1) The IUVP emission
levels exceed the applicable certification emission standard 50% or
more of the test vehicles and (2) the average emission level is at
least 1.3 times the applicable emission standard. These criteria would
be evaluated independently for all applicable FTP emission
constituents. Each constituent should be considered separately in this
analysis.
    The Agency may, from time to time, require manufacturers to analyze
available IUVP data, or other information, when it indicates that the
durability objective is not being achieved for some portion of the
fleet of vehicles covered by a durability procedure. This provision
would apply whether or not the screening criteria are exceeded.
    As in the CAP 2000 program, EPA 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. The
Agency will 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. 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.
    If the manufacturer was using the standard road cycle or standard
bench cycle, EPA will require the manufacturer to adjust the durability
process so it would achieve the durability objective. The Agency will
allow 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