Previously, complete vehicles with a Gross Vehicle Weight Rating of 8,500-14,000 pounds could be certified according to 40 CFR part 86, subpart S.  These heavy-duty chassis certified vehicles were required to pass emissions on both the Light-duty FTP and HFET (California requirement).  These  rules will use the same testing procedures already required for heavy-duty chassis certification, namely the Light-duty FTP and the HFET but extend the requirement for chassis certification for CO2 emissions to diesel-powered vehicles.  Using the data from these two tests, EPA and NHTSA will compare the CO2 emissions and fuel consumption results against the attribute-based target.  The attribute upon which the CO2 standard is based is a function of vehicle payload, vehicle towing capacity and two-wheel versus four-wheel drive configuration.  The attribute-based standard targets will be used to determine a manufacturer fleet standard and is subject to an average banking and trading scheme similar to the light-duty GHG rule.
This rule will require nearly all heavy-duty trucks between 8,500 and 14,000 pounds gross vehicle weight rating that are not already covered under the light-duty truck and medium-duty passenger vehicle GHG standards to have a CO2, CH4 and N2O values assigned to them, either from actual chassis dynamometer testing or from the results of a representative vehicle in the test group with appropriate adjustments made for differences.  This requirement will apply based on whether the vehicle manufacturer sold the vehicle as a complete or nearly complete vehicle.  Manufacturers will be allowed to exclude vehicles they sell to secondary manufacturers without cabs (often known as rolling chassis), as well as a very small number of vehicles sold with cabs.  Specifically, a manufacturer can certify up to two percent of its vehicles with complete cabs, or up to 2,000 vehicles if its total sales in this category was less than 100,000, as vocational vehicles.  To the extent manufacturers are allowed to engine certify for criteria pollutant (non-GHG) requirements today, they will be allowed to continue to do so under the final regulations.
Because this program for heavy-duty pickup trucks and vans is so similar to the program recently adopted for light-duty trucks and codified in 40 CFR part 86, subpart S, EPA will apply most of those subpart S regulatory provisions to heavy-duty pickup trucks and vans and to recodify them in the new part 1037.  Most of the new part 1037 would not apply for heavy-duty pickup trucks and vans.  How 40 CFR part 86 applies, and which provisions of the new 40 CFR part 1037 apply for heavy-duty pickup trucks and vans is described in §1037.104.
Certification Process
CAA section 203(a)(1) prohibits manufacturers from introducing a new motor vehicle into commerce unless the vehicle is covered by an EPA-issued certificate of conformity.  Section 206(a)(1) of the CAA describes the requirements for EPA issuance of a certificate of conformity, based on a demonstration of compliance with the emission standards established by EPA under section 202 of the Act.  The certification demonstration requires emission testing, and certification is required for each model year.
Under existing heavy-duty chassis certification and other EPA emission standard programs, vehicle manufacturers certify a group of vehicles called a test group.  A test group typically includes multiple vehicle car lines and model types that share critical emissions-related features.
EPA requires the manufacturer to make a good faith demonstration in the certification application that vehicles in the test group will both 1) comply throughout their useful life within the emissions bin assigned, and 2) contribute to fleetwide compliance with the applicable emissions standards when the year is over.  EPA issues a certificate for the vehicles included in the test group based on this demonstration, and includes a condition in the certificate that if the manufacturer does not comply with the fleet average, then production vehicles from that test group will be treated as not covered by the certificate to the extent needed to bring the manufacturer's fleet average into compliance with the applicable standards.
The certification process often occurs several months prior to production and manufacturer testing may occur months before the certificate is issued.  The certification process for the existing heavy-duty chassis program is an efficient way for manufacturers to conduct the needed testing well in advance of certification, and to receive certificates in a time frame which allows for the orderly production of vehicles.  The use of conditions on the certificate has been an effective way to ensure that manufacturers comply throughout their useful life and meet fleet standards when the model year is complete and the accounting for the individual model sales is performed.  EPA has also adopted this approach as part of its LD GHG compliance program.
This rule will similarly condition each certificate of conformity for the GHG program upon a manufacturer's good faith demonstration of compliance with the manufacturer's fleetwide average CO2 standard.  The following discussion explains how EPA will integrate this new vehicle certification program into the existing certification program.
An integrated approach with NHTSA has been undertaken to allow manufacturers a single point of entry to address certification and compliance.  Vehicle manufacturers will initiate the formal certification process with their submission of application for a certificate of conformity to EPA similar to the light duty program.
Certification Test Groups and Test Vehicle Selection
For heavy-duty chassis certification to the criteria emission standards, manufacturers currently, as mentioned above, divide their fleet into "test groups" for certification purposes.  The test group is EPA's unit of certification; one certificate is issued per test group/ evaporative family combination.  These groupings cover vehicles with similar emission control system designs expected to have similar emissions performance (see 40 CFR 86.1827-01).  The factors considered for determining test groups include Gross Vehicle Weight, combustion cycle, engine type, engine displacement, number of cylinders and cylinder arrangement, fuel type, fuel metering system, catalyst construction and precious metal composition, among others.  Vehicles having these features in common are generally placed in the same test group.
This rule will retain the current test group structure for heavy-duty pickups and vans in the certification requirements for CO2.  At the time of certification, manufacturers will use the CO2 emission level from the Emission Data Vehicle as a surrogate to represent all of the models in the test group.  However, following certification further testing will generally be allowed for compliance with the fleet average CO2 standard as described below.  EPA's issuance of a certificate will be conditioned upon the manufacturer's subsequent model level testing and attainment of the actual fleet average, much like light-duty CAFE and GHG compliance requires.  Under the current program, complete heavy-duty Otto-cycle vehicles under 14,000 pounds Gross Vehicle Weight Rating are required to chassis certify (see 40 CFR 86.1801-01(a)).  The current program allows complete heavy-duty diesel vehicles under 14,000 pounds GVWR to optionally chassis certify (see 40 CFR 86.1863-07(a)).  As discussed earlier, this rule will now require all HD vehicles under 14,000 pounds GVWR to chassis certify except as noted in Section II. EPA recognizes that the existing heavy-duty chassis test group criteria do not necessarily relate to CO2 emission levels.  See 75 FR 25472.  For instance, while some of the criteria, such as combustion cycle, engine type and displacement, and fuel metering, may have a relationship to CO2 emissions, others, such as those pertaining to the some exhaust aftertreatment features, may not.  In fact, there are many vehicle design factors that impact CO2 generation and emissions but are not major factors included in EPA's test group criteria.  Most important among these may be vehicle weight, horsepower, aerodynamics, vehicle size, and performance features.  To remedy this, EPA will allow manufacturers provisions that are similar to the LD GHG rule that would yield more accurate CO2 estimates than only using the test group emission data vehicle CO2 emissions.
EPA believes that the current test group concept is appropriate for N2O and CH4 because the technologies that would be employed to control N2O and CH4 emissions may generally be the same as those used to control the criteria pollutants. However, manufacturers will determine if this approach is adequate method for N2O and CH4 emissions compliance or if testing on additional vehicles is required to ensure their entire fleet meets applicable standards.
As just discussed, the "worst case" vehicle a manufacturer selects as the Emissions Data Vehicle to represent a test group under the existing regulations (40 CFR 86.1828-01) may not have the highest levels of CO2 in that group.  For instance, there may be a heavier, more powerful configuration that would have higher CO2, but may, due to the way the catalytic converter has been matched to the engine, actually have lower NOX, CO, PM or HC emissions.  Therefore, EPA is allowing the use of a single Emission Data Vehicle to represent the test group for both criteria pollutant and CO2 certification. The manufacturer will be allowed to initially apply the Emission Data Vehicle's CO2 emissions value to all models in the test group, even if other models in the test group are expected to have higher CO2 emissions. However, as a condition of the certificate, this surrogate CO2 emissions value will generally be replaced with actual, model-level CO2 values based on results from additional testing that occurs later in the model year much like the light-duty CAFE program, or through the use of approved methods for analytically derived fuel economy. This model level data will become the official certification test results (as per the conditioned certificate) and will be used to determine compliance with the fleet average.  If the test vehicle is in fact the worst case CO2 vehicle for the test group , the manufacturer may elect to apply the Emission Data Vehicle emission levels to all models in the test group for purposes of calculating fleet average emissions. Manufacturers may be unlikely to make this choice, because doing so would ignore the emissions performance of vehicle models in their fleet with lower CO2 emissions and would unnecessarily inflate their CO2 fleet average.  Testing at the model level, in order to better represent the improved performance of vehicles within a test group other than the Emission Data Vehicle, will necessarily increase testing burden beyond the minimum EDV testing.
As explained in earlier Sections, there are two standards that the manufacturer will be subject to, the fleet average standard and the in-use standard for the useful life of the vehicle.  Compliance with the fleet average standard is based on production weighted averaging of the test data that applies for each model.  To address commenter concerns regarding test variability due to facility and build variation  for each model, the in-use and SEA standards are set at 10 percent higher than the level used for that model in calculating the fleet average.  The certificate covers both of the fleet and in-use standards, and the manufacturer has to demonstrate compliance with both of these standards for purposes of receiving a certificate of conformity.  The certification process for the in-use standard is discussed above.
Pre-Model Year (or Compliance Plan) Reporting
EPA and NHTSA are requiring that manufacturers submit a compliance plan for their entire fleet prior to the certification of any test group in a given model year.  Preferably, this compliance plan would be submitted at the manufacturer's annual certification preview meeting. This preview meeting is typically held before the earliest date that the model year can begin.  The earliest a model year can begin is January 2[nd] of the calendar year prior to the model year.  This plan should include the manufacturer's estimate of its attribute-based standard, along with a demonstration of compliance with the standard based on projected model-level CO2 emissions and fuel consumption, and production estimates.  This information will be similar to the information submitted to NHTSA and EPA in the pre-model year report required for CAFE compliance for light-duty vehicles.  Included in the compliance plan, manufacturers seeking to take advantage of credit flexibilities will include these in their compliance demonstration.  Similarly, the compliance demonstration will need to include a credible plan for addressing deficits accrued in prior model years.  EPA and NHTSA will review the compliance plan for technical viability and conduct a certification preview discussion with the manufacturer.  The agencies will view the compliance plan as part of the manufacturer's good faith demonstration, but understands that initial projections can vary considerably from the reality of final production and emission results.  In addition, the compliance plan must be approved by the EPA Administrator prior to any certificate of compliance being issued.
Demonstrating compliance
CO2 and Fuel Consumption Fleet Standards
  As noted, attribute-based CO2 standards result in each manufacturer having a fleet average CO2 standard unique to its heavy-duty truck fleet of GVWR between 8,500-14,000 pounds and that standard will be separate from the standard for passenger cars, light-trucks, and other heavy-duty trucks.  The standards depend on those attributes corresponding to the relative capability, or "work factor", of the vehicle models produced by that manufacturer. The final attributes used to determine the stringency of the  CO2 standard are payload and towing capacity as described in Section II. .  Generally, fleets with a mix of vehicles with increased payloads or greater towing capacity (or utilizing four wheel drive configurations) will face numerically less stringent standards (i.e., higher CO2 grams/mile standards) than fleets consisting of less powerful vehicles.  (However, the standards will be expected to be equally challenging and achieve similar percent reductions.)  Although a manufacturer's fleet average standard could be estimated throughout the model year based on projected production volume of its vehicle fleet, the final compliance values will be based on the final model year production figures.  A manufacturer's calculation of fleet average emissions at the end of the model year will be based on the production-weighted average emissions of each model in its fleet.  The payload and towing capacity inputs used to determine manufacturer compliance will be the advertised values.
The agencies will use the same general vehicle category definitions that are used in the current EPA HD chassis certification (See 40 CFR 86.1816-05).  The new vehicle category definitions differ slightly from the EPA definitions for Heavy-duty Vehicle definitions for the existing program, as well as other EPA vehicle programs.  Mainly, manufacturers will be able to test, and possibly model, more configurations of vehicles than were historically.  The existing criteria pollutant program requires the worst case configuration be tested for emissions certification.  For HD chassis certification, this usually meant only testing the vehicle with the highest ALVW, road-load, and engine displacement within a given test group.   This worst case configuration may only represent a small fraction of the test group production volume.  By testing the worst case, albeit possibly small volume, vehicle configuration, the EPA had a reasonable expectation that all represented vehicles would pass the given emissions standards.  Since CO2 standards are a fleet standard based on a combination of sales volume and work factor (i.e., payload and towing capability), it may be in a manufacturer's best interest to test multiple configurations within a given test group to more accurately estimate the fleet average CO2 emission levels and not accept the worst case vehicle test results as representative of all models. Additionally, vehicle models for which a manufacturer desires to use analytically derived fuel economy (ADFE) to estimate CO2 emission levels may need additional actual test data for vehicle models of similar but not identical configurations.   The agencies are allowing the use of ADFE similar to that allowed for light-duty vehicles in 40 CFR 600.006-08(e).  Some commenters, including the American Automotive Policy Council, were concerned that adopting the light duty ADFE program with its current minimum test requirements would unduly increase testing burden.  In addition to concerns over implementing the light duty ADFE program for heavy duty GHG compliance, commenters noted the need to develop a new HD ADFE methodology that addressed unique HD concerns.  EPA and NHTSA have continued to work with stakeholders to address the above concerns with using a modified LD ADFE program.  To address these concerns, the agencies will expand the allowed use of ADFE beyond that which is allowed in the LD program.  Since ADFE equations are not final at the time of this rule, updates to the HD ADFE program will be made through guidance or future rulemaking.   The GHG and fuel economy rulemaking for light-duty vehicles adopted a carbon balance methodology used historically to determine fuel consumption for the light-duty labeling and CAFE programs, whereby the carbon-related combustion products HC and CO are included on an adjusted basis in the compliance calculations, along with CO2.  The resulting carbon-related exhaust emissions (CREE) of each test vehicle are calculated and it is this value, rather than simply CO2 emissions, that is used in compliance determinations.  The difference between the CREE and CO2 is typically very small.
NHTSA and EPA are not adopting the CREE methodology for HD pickups and vans, and so will not adjust CO2 emissions to further account for additional HC and CO.  The basis of the CREE methodology in historical labeling and CAFE programs is not relevant to HD pickups and vans, because these historical programs do not exist for HD vehicles.  Furthermore, test data used in this proposal for standards-setting has not been adjusted for this effect, and so it would create an inconsistency, albeit a small one, to apply it for compliance with the numerical standards we are finalizing.  Finally, it would add complexity to the program with little real world benefit.
CO2 In-Use Standards and Testing
Section 202(a)(1) of the CAA requires emission standards to apply to vehicles throughout their statutory useful life.  Section II discusses in-use standards.
Currently, EPA regulations require manufacturers to conduct in-use testing as a condition of certification for heavy-duty trucks between 8,500 and 14,000 gross vehicle weight that are chassis certified.  The vehicles are tested to determine the in-use levels of criteria pollutants when they are in their first and third years of service.  This testing is referred to as the In-Use Verification Program, which was first implemented as part of EPA's CAP 2000 certification program (see 64 FR 23906, May 4, 1999).
An in-use program was already set forth in the 2012  -  2016 MY light-duty vehicle rule similar to the proposed heavy-duty pickups and vans. The In-Use Verification Program for heavy-duty pickups and vans will follow the same general provisions of the light-duty program in regard to testing, vehicle selection, and reporting.  See 75 FR 25474-25476.
Cab-Chassis Vehicles and Complete Class 4 Vehicles
As discussed in Section I.C(2)(a), we are including most cab-chassis Class 2b and 3 vehicles in the complete HD pickup and van program.  Because their numbers are relatively small, and to reduce the testing and compliance tracking burden to manufacturers, we would treat these vehicles as equivalent to the complete van or truck product they are derived from.  The manufacturer would determine which complete vehicle configuration it produces most closely matches the cab-chassis product leaving its facility, and would include each of these cab-chassis vehicles in the fleet averaging calculations as though it were identical to the corresponding complete vehicle.
Any in-use testing of these vehicles would do likewise, with loading of the tested vehicle to a total weight equal to the ALVW of the corresponding complete vehicle configuration.  If the secondary manufacturer had altered or replaced any vehicle components in a way that would substantially affect CO2 emissions from the tested vehicle (e.g., axle ratio has been changed for a special purpose vehicle), the vehicle manufacturer could request that EPA not test the vehicle or invalidate a test result.  Secondary (finisher) manufacturers would not be subject to requirements under this provision, other than to comply with anti-tampering regulations.  However, if they modify vehicle components in such a way that GHG emissions and fuel consumption are substantially affected, they become manufacturers subject to the standards under this proposal.
We realize that this approach does not capture the likely loss of aerodynamic efficiency involved in converting these vehicles from standard pickup trucks or vans to ambulances and the like, and thus it could assign them lower GHG emissions and fuel consumption than they deserve.  However, we feel that this approach strikes a fair balance between the alternatives -- grouping these vehicles with vocational vehicles subject only to engine standards and tire requirements, or creating a complex and burdensome program that forces vehicle manufacturers to track, and perhaps control, a plethora of vehicle configurations they currently do not manage.  We request comment on this final provision and any suggestions for ways to improve it.
EPA and NHTSA requested comment on whether Class 4 trucks that are very similar to complete Class 3 pickup truck models should be regulated as part of the HD pickup and van category, instead of as vocational vehicles.  Commenters argued convincingly that there are a number of important differences between the Class 4 and Class 3 trucks that make such regulation inappropriate.  As a result, we are keeping Class 4 trucks in the vocational vehicle category.
 Labeling Provisions
HD pickups and vans currently have vehicle emission control information labels showing compliance with criteria pollutant standards, similar to emission control information labels for engines. As with engines, we believe this label is sufficient.
Other Certification Issues
Carryover Certification Test Data
EPA's final certification program for vehicles allows manufacturers to carry certification test data over from one model year to the next, when no significant changes to models are made. EPA will also apply this policy to CO2, N2O and CH4 certification test data.
Compliance Fees
The CAA allows EPA to collect fees to cover the costs of issuing certificates of conformity for the classes of vehicles and engines covered by this proposal. On May 11, 2004, EPA updated its fees regulation based on a study of the costs associated with its motor vehicle and engine compliance program (69 FR 51402). At the time that cost study was conducted the current rulemaking was not considered.
At this time the extent of any added costs to EPA as a result of this proposal is not known. EPA will assess its compliance testing and other activities associated with the rule and may amend its fees regulations in the future to include any warranted new costs.
 Compliance Reports
Pre-Model Year Report
In the NPRM, EPA and NHTSA proposed that manufacturers must submit early model year compliance reports demonstrating how their entire fleets of heavy-duty pickup trucks and vans would comply with GHG emissions and fuel consumption standards.  The agencies understood that early model year reports would contain estimates that may change over the course of a model year and that compliance information manufactures submit prior to the beginning of a new model year may not represent the final compliance outcome.  The agencies viewed the necessity for requiring early model reports as a manufacturer's good faith projection for demonstrating compliance with emission and fuel consumption standards.   The preamble language indicated that the compliance reports would be submitted prior to the beginning of the model year and prior to the certification of any test group.  Preferably, a manufacturer would submit its reports during its annual certification preview meeting.    Precertification preview meetings are typically held with a manufacturer before the earliest date that the model year can begin which is January 2nd of the calendar year prior to the model year.   Manufacturers voluntarily choose to participate in precertification compliance meetings but meetings are not required by EPA and NHTSA regulations.  Manufacturers opt to participate in precertification meetings because of the advantage it gives to exploring with the agencies any possible compliance problems that may arise prior to seeking approval for certificates of conformity.   The NPRM preamble text did not specify an exact date for manufacturers to submit early compliance reports to the agency.  NHTSA attempted to adopt requirements in its regulatory text for manufactures to submit their early compliance reports no later than the end of December two years prior to the model year.  NHTSA also proposed for manufacturers to provide compliance information for the current model year and to the extent possible two years into the future.  NHTSA chose its submission deadline and model years for reporting based upon the same dates required by EPA in its CAFE provisions for light duty pickups and vans beginning in model year 2012.
The NPRM included requirements for manufacturers to submit early model year compliance reports separately to each agency based upon limitations existing in the statutory authorities prescribed under EISA and CAA and the long-standing precedent set in the LD CAFE programs for receiving reports.  The EPA report, called the pre-model year report, and NHTSA report, called the pre-certification compliance report, were proposed to include an estimate of the manufacturer's attribute-based standards, along with a demonstration of compliance with the standards based on projected model-level and fleet CO2 emissions and fuel consumption results, and were to include an estimate of the manufacturer's production volumes.  The NPRM also included a proposal for submitting a credit plan for manufacturers seeking to take advantage of credit flexibilities and a credit deficit plan for manufacturers planning to accrue deficits during the model years.  Additionally, NHTSA attempted to reduce the burden on manufacturers by allowing them to submit copies of EPA's proposed pre-model year reports or applications for certifications of conformity, as a substitute to its own compliance report, so long as EPA's reports were submitted with equivalent fuel consumption information.  In either case, NHTSA reserved the right to ask manufacturers to provide additional information if necessary to verify its fuel consumption requirements under this program.  EPA and NHTSA also proposed to review the compliance reports for technical viability and to conduct a certification preview discussion with the manufacturer.  It was further proposed that the EPA Administrator would have to approve a manufacturer's compliance plan before it would consider issuing any certificate of compliance for the manufacturer.
Comments were received to the NPRM from EMA and TMA strongly opposing providing separate reports to EPA and NHTSA and requested that the agencies implement a single uniform reporting template that could be submitted to both agencies simultaneously.  DTNA requested that NHTSA eliminate its pre-certification compliance report, arguing that report was overly burdensome.
For the final rule, the agencies have decided to require manufacturers to submit a single report, hereafter referenced as the pre-model year report, to satisfy both agencies requirements for receiving compliance reports in advance of the model year.   The agencies considered the commenters' requests and determined that the benefit gained by receiving separate or distinct compliance reports would not outweigh the burden placed on manufacturers in reporting.  Therefore, the final rule establishes a harmonized approach by which manufacturers will submit a single report through the EPA database system as the single point of entry for all information required for this national program and both agencies will have access to the information.  If by model year 2012, the agencies are not prepared to receive information through the EPA database system, manufacturers are expected to submit written reports to the agencies.  EPA and NHTSA have determined that requiring manufacturers to submit a joint pre-model year report for their combined fleet of heavy-duty pickup trucks containing both emissions and equivalent fuel consumption information falls within each agencies' statutory authority.   The final rule requires a manufacturer to submit the joint pre-model year report as early as the date of the manufacturer's annual certification preview meeting, or prior to the manufacturer submitting its first application for a certificate for the given model year.    Consequently, a manufacturer choosing to comply in model year 2014 could submit its pre-model year report during its precertification meeting which could occur before January 2, 2013, or could provide its pre-model year report any time prior to submitting its first application.   In either case, a manufacturer would not be able to certify any of its test groups until the EPA Administrator approves its pre-model year report.  NHTSA will use the pre-model year report as preliminary model year data.
The final rule adopts for the pre-model year reports similar requirements as proposed in the NPRM.  As mention, the NPRM proposed for reports to include an estimate of the manufacturer's attribute-based standards, expected testing results and estimated production volumes.  The agencies agree that this information is essential for tracking compliance of manufacturers and is therefore adopted for the final rule.  As discussed in the NPRM, the final rule requires manufacturers to identify any vehicle exclusions and other flexibilities afford for heavy-duty pickup and vans. The summary of the required information for each pre-model year report is as follows:
         * A list of each unique vehicle configuration included in the manufacturer's fleet describing the make and model designations, attribute based-values (GVWR, GCWR, Curb Weight and drive configurations) and standards.
         * The emission and fuel consumption fleet average standard derived from the unique vehicle configurations;
         * The estimated vehicle configuration, test group and fleet production volumes;
         * The expected emissions and  fuel consumption test group results and fleet average performance;
         * A statement declaring whether the manufacturer will use fixed or increasing standards; acknowledging that once selected, the decision cannot be reversed and the manufacturer must continue to comply with the same alternative for subsequent model years;
         * A statement declaring whether the manufacturer chooses to comply early in MY 2013 for EPA and NHTSA.  The manufacturers must acknowledge that once selected, the decision cannot be reversed and the manufacturer will continue to comply with the fuel consumption standards for subsequent model years;
         * A statement declaring whether the manufacturer chooses to comply voluntarily with NHTSA's fuel consumption standards for model years 2014 through 2015.  The manufacturers must acknowledge that once selected, the decision cannot be reversed and the manufacturer will continue to comply with the fuel consumption standards for subsequent model years;
         * The list of cab-complete vehicles and the method use to certify, as vocational vehicles and engines, or as complete pickups and vans identifying the most similar complete vehicles used to derive the target standards and performance test results;
         * The list of vehicles a manufacturer is designating to include in the low volume exclusion; and
         * A credit plan identifying the manufacturers estimated credit balances, planned credit flexibilities (i.e., credit balances, planned credit trading, innovative, advanced and early credits and etc.) and if needed a credit deficit plan demonstrating how it plans to resolve any credit deficits that might occur for a model year within a period of up to three model years after that deficit has occurred.
Final Reports
The NPRM proposed for manufacturers participating in the ABT program to provide two types of year end reports; end-of-the-year (EOY) reports and final reports.  The EOY reports for the ABT program were required to be submitted by manufacturers no later than 90 days after the calendar year and final report no later than 270 days after the calendar year.  Manufacturers not participating in the ABT program were required to provide an EOY report within 45 days after the calendar year but no final reports were required.  The final ABT report due was established coinciding with EPA's existing criteria pollutant report for heavy-duty engines.  The EOY report was required in order to receive preliminary final estimates and identifies manufacturers that might have a credit deficit for the given model year.  Manufacturers with a credit surplus at the end of each model could receive a waiver from providing EOY reports.  As proposed, the remaining manufacturers were required to submit reports to EPA and send copies of those reports to NHTSA with equivalent fuel consumption values.
Comments in response to the NPRM requested that for manufacturers not using ABT provisions, the EOY report due 90 days after the end of the calendar year should be combined with the ABT report due 90 days after the same model year.  Commenters also requested that the exempted off-road vehicle report be consolidated with the EOY report.
For the final rule, the agencies will retain the NPRM proposal for EOY and final reports.  The final rule establishes a harmonized approach by which manufacturers will submit a single report through the EPA database system as the single point of entry for all information required for this national program and both agencies will have access to the information.  If by model year 2012, the agencies are not prepared to receive information through the EPA database system, manufacturers are expected to submit written reports to the agencies.  The agencies are also combining the EOY reports for all manufacturers whether or not using the ABT program.  A summary of the required information in the final rule for EOY and final reports is as follows:
         * A finalized list of each unique vehicle configuration included in the manufacturers fleet describing the designations, attribute based-values (GVWR, GCWR, Curb Weight and drive configurations) and standards.
         * The final emission and fuel consumption fleet average standard derived from the unique vehicle configurations;
         * The final vehicle configuration, test group and fleet production volumes;
         * The final emissions and  fuel consumption test group results and fleet average performance;
         * The final list of cab-complete vehicles and the method use to certify, as vocational vehicles and engine, or as complete pickups and vans identifying the most similar complete vehicles used to derive the target standards and performance test results;
         * The final list of vehicles a manufacturer is designating to include in the low volume exclusion;
         * A final credit plan identifying the manufacturers estimated credit balances, planned credit flexibilities (i.e., credit balances, planned credit trading, innovative, advanced and early credits and etc.) and if needed a credit deficit plan demonstrating how it plans to resolve any credit deficits that might occur for a model year within a period of up to three model years after that deficit has occurred;
         * A plan describing the vehicles that were exempted such as for off-road or small business purposes; and
         * A plan describing any alternative fueled vehicles that were produced for the model year identifying the approaches used to determinate compliance and the production volumes.
Heavy-Duty Engines
 Compliance Approach
Section 203 of the CAA requires that all motor vehicles and engines sold in the United States to carry a certificate of conformity issued by the US EPA.  For heavy-duty engines, the certificate specifies that the engine meets all requirements as set forth in the regulations (40 CFR part 86, subpart N, for criteria pollutants) including the requirement that the engine be compliant with emission standards.  This demonstration is completed through emission testing as well as durability testing to determine the level of emissions deterioration throughout the useful life of the engine. In addition to compliance with emission standards, manufacturers are also required to warrant their products against emission defects, and demonstrate that a service network is in place to correct any such conditions.  The engine manufacturer also bears responsibility in the event that an emission-related recall is necessary.  Finally, the engine manufacturer is responsible for tracking and ensuring correct installation of any emission related components installed by a second party (i.e., vehicle manufacturer).  EPA believes this compliance structure is also valid for administering the final GHG regulations for heavy-duty engines.
Certification Process
In order to obtain a certificate of conformity, engine manufacturers must complete a compliance demonstration, normally consisting of test data from relatively new (low-hour) engines as well as supporting documentation, showing that their product meets emission standards and other regulatory requirements.  To account for aging effects, low-hour test results are coupled with testing-based deterioration factors (DFs), which provide a ratio (or offset) of end-of-life emissions to low-hour emissions for each pollutant being measured.  These factors are then applied to all subsequent low-hour test data points to predict the emissions behavior at the end of the useful life.
For purposes of this compliance demonstration and certification, engines with similar engine hardware and emission characteristics throughout their useful life may be grouped together in engine families, consistent with current criteria-pollutant certification procedures.  Examples of such characteristics are the combustion cycle, aspiration method, and aftertreatment system.  Under this system, the worst-case engine ("parent rating") is selected based on having the highest fuel feed per engine stroke, and all emissions testing is completed on this model.  All other models within the family ("child ratings") are expected to have emissions at or below the parent model and therefore in compliance with emission standards.  Any engine within the family can be subject to selective enforcement audits, in-use, confirmatory, or other compliance testing.
We are continuing the use of this approach for the selection of the worst-case engine ("parent rating") for fuel consumption and GHG emissions as well.  We believe this is appropriate because this worst case engine configuration would be expected to have the highest in-use fuel consumption and GHG emissions within the family.  We note that lower engine ratings contained within this family would be expected to have a higher fuel consumption rate when measured over the Federal Test Procedures as expressed in terms of fuel consumption per brake horsepower hour.  This higher fuel consumption rate is misleading in the context of comparing engines within a single engine family.  This apparent contradiction can be most easily understood in terms of an example.  For a typical engine family a top rating could be 500 horsepower with a number of lower engine ratings down to 400 horsepower or lower included within the family.  When installed in identical trucks the 400 and 500 horsepower engines would be expected to operate identically when the demanded power from the engines is 400 horsepower or less.  So in the case where in-use driving never included acceleration rates leading to horsepower demand greater than 400 horsepower, the two trucks with the 400 and 500 horsepower engines would give identical fuel consumption and GHG performance.  When the desired vehicle acceleration rates were high enough to require more than 400 horsepower, the 500 horsepower truck would accelerate faster than the 400 horsepower truck resulting in higher average speeds and higher fuel consumption and GHG emissions measured on a per mile or per ton-mile basis.  Hence, the higher rated engine family would be expected to have the highest in-use fuel consumption and CO2 emissions.
The reason that the lower engine ratings appear to have worse fuel consumption relates to our use of a brake specific work metric.  The brake specific metric measures power produced from the engine and delivered to the vehicle ignoring the parasitic work internal to the engine to overcome friction and air pumping work within the engine.  The fuel consumed and GHG emissions produced to overcome this internal work and to produce useful (brake) work are both measured in the test cycle but only the brake work is reflected in the calculation of the fuel consumption rate.  This is desirable in the context of reducing fuel consumption as this approach rewards engine designs that minimize this internal work through better engine designs.  The less work that is needed internal to the engine, the lower the fuel consumption will be.  If we included the parasitic work in the calculation of the rate, we would provide no incentive to reduce internal friction and pumping losses.  However, when comparing two engines within the very same family with identical internal work characteristics, this approach gives a misleading comparison between two engines as described above.  This is the case because both engines have an identical fuel consumption rate to overcome internal work but different rates of brake work with the higher horsepower rating having more brake work because the test cycle is normalized to 100 percent of the engine's rated power.  The fuel consumed for internal work can be thought of as a fixed offset identical between both engines.  When this fixed offset is added to the fuel consumed for useful (brake) work over the cycle, it increases the overall fuel consumption (the numerator in the rate) without adding any work to the denominator.  This fixed offset identical between the two engines has a bigger impact on the lower engine rating.  In the extreme this can be seen easily.  As the engine ratings decrease and approach zero, the brake work approaches zero and the calculated brake specific fuel consumption approaches infinity. For these reasons, we are finalizing that the same selection criteria, as outlined in 40 CFR part 86, subpart N, be used to define a single engine family designation for both criteria pollutant and GHG emissions.  Further, we are finalizing that for fuel consumption and CO2 emissions only any selective enforcement audits, in-use, confirmatory, or other compliance testing would be limited to the parent rating for the family. This approach is being contemplated for administrative convenience and we seek comments on alternatives to address compliance testing.  Consistent with the current regulations, manufacturers may electively subdivide a grouping of engines which would otherwise meet the criteria for a single family if they have evidence that the emissions are different over the useful life.
The agency utilizes a 12-digit naming convention for all mobile-source engine families (and test groups for light-duty vehicles).  This convention is also shared by the California Air Resources Board which allows manufacturers to potentially use a single family name for both EPA and California ARB certification. Of the 12 digits, 9 are EPA-defined and provide identifying characteristics of the engine family.  The first digit represents the model year, through use of a predefined code. For example, "A" corresponds to the 2010 model year and "B" corresponds to the 2011 model year.  The 5[th] position corresponds to the industry sector code, which includes such examples as light-duty vehicle (V) and heavy-duty diesel engines (H). The next three digits are a unique alphanumeric code assigned to each manufacturer by EPA.  The next four digits describe the displacement of the engine; the units of which are dependent on the industry segment and a decimal may be used when the displacement is in liters.  For engine families with multiple displacements, the largest displacement is used for the family name.  For on-highway vehicles and engines, the tenth character is reserved for use by California ARB. The final characters (including the 10[th] character in absence of California ARB guidance) left to the manufacturer to determine, such that the family name forms a unique identifying characteristic of the engine family.
This convention is well understood by the regulated industries, provides sufficient detail, and is flexible enough to be used across a wide spectrum of vehicle and engine categories.  In addition, the current harmonization with other regulatory bodies reduces complications for affected manufacturers. For these reasons, we are not finalizing any major changes to this naming convention for this proposal.  There may be additional categories defined for the 5[th] character to address heavy-duty vehicle families, however that will be discussed later.
As with criteria pollutant standards, the heavy-duty diesel regulatory category is subdivided into three regulatory subcategories, depending on the GVW of the vehicle in which the engine will be used.  These regulatory subcategories are defined as light-heavy-duty (LHD) diesel, medium heavy-duty (MHD) diesel, and heavy heavy-duty (HHD) diesel engines. All heavy-duty gasoline engines are grouped into a single subcategory. Each of these regulatory subcategories are expected to be in service for varying amounts of time, so they each carry different regulatory useful lives.  For this reason, expectations for demonstrating useful life compliance differ by subcategory, particularly as related to deterioration factors.
Light heavy-duty diesel engines (and all gasoline heavy-duty engines) have the same regulatory useful life as a light-duty vehicle (110,000 miles), which is significantly shorter than the other heavy-duty regulatory subcategories. Therefore, we believe it is appropriate to maintain commonality with the light-duty GHG rule.  During the light-duty GHG rulemaking, the conclusion was reached that no significant deterioration would occur over the useful life. Therefore, EPA is recommending that manufacturers use assigned DFs for CO2.  For this final action, we believe appropriate values are zero (for additive DFs) and one (for multiplicative DFs).  EPA will continue to collect data regarding deterioration of CO2 emissions and may revisit these assigned values if necessary.
For the medium heavy-duty and heavy heavy-duty diesel engine segments, the regulatory useful lives are significantly longer (185,000 and 435,000 miles, respectively).  For this reason, the agency is not convinced that engine/aftertreatment wear will not have a negative impact on GHG emissions. To address useful life compliance for MHD and HHD diesel engines certified to GHG standards, we believe the criteria pollutant approach for developing DFs is appropriate. Using CO2 as an example, many of the engine deterioration concerns previously identified will affect CO2 emissions. Reduced compression, as a result of wear, will cause higher fuel consumption and increase CO2 production.  In addition, as aftertreatment devices age (primarily particulate traps), regeneration events may become more frequent and take longer to complete. Since regeneration commonly requires an increase in fuel rate, CO2 emissions would likely increase as well. Finally, any changes in EGR levels will affect heat release rates, peak combustion temperatures, and completeness of combustion.  Since these factors could reasonably be expected to change fuel consumption, CO2 emissions would be expected to change accordingly.
HHD diesel engines may also require some degree of aftertreatment maintenance throughout their useful life.  For example, one major heavy-duty engine manufacturer specifies that their diesel particulate filters be removed and cleaned at intervals between 200,000 and 400,000 miles, depending on the severity of service. Another major engine manufacturer requires servicing diesel particulate filters at 300,000 miles. This maintenance or lack thereof if service is neglected, could have serious negative implications to CO2 emissions. In addition, there may be emissions-related warranty implications for manufacturers to ensure that if rebuilding or specific emissions related maintenance is necessary, it will occur at the prescribed intervals.  Therefore, it is imperative that manufacturers are detailed in their maintenance instructions.  Lean-NOX aftertreatment devices may also facilitate GHG reductions by allowing engines to run with higher engine-out NOX levels in exchange for more efficient calibrations. In most cases, these aftertreatment devices require a consumable reductant, such as diesel exhaust fluid, which requires periodic maintenance by the vehicle operator.  Without such maintenance, the emission control system may be compromised and compliance with emission standards may be jeopardized.  Such maintenance is considered to be critical emission related maintenance and manufacturers must therefore demonstrate that it is likely to be completed at the required intervals.  One example of such a demonstration is an engine power de-rating strategy that will limit engine power or vehicle speed in absence of this required maintenance.
If the manufacturer determines that maintenance is necessary on critical emission-related components within the useful life period, they must have a reasonable basis for ensuring that this maintenance will be completed as scheduled. This includes any adjustment, cleaning, repair, or replacement of critical emission-related components. Typically, the agency has only allowed manufacturers to schedule such maintenance if the manufacturer can demonstrate that the maintenance is reasonably likely to be done at the recommended intervals.  This demonstration may be in the form of survey data showing at least 80 percent of in-use engines get the prescribed maintenance at the correct intervals. Another possibility is to provide the maintenance free of charge.  We see no reason to depart from this approach for GHG-related critical emission-related components.
Demonstrating Compliance With the  Standards
CO2 Standards
The final test results (adjusted for deterioration, if applicable) form the basis for the Family Certification Limit (FCL), which the manufacturer must specify to be at or above the certification test results. This FCL becomes the emission standard for the family and any certification or confirmatory testing must show compliance with this limit.  In addition, manufacturers may choose an FCL at any level above their certified emission level to provide a larger compliance margin.  If subsequent certification or confirmatory testing reveals emissions above the FCL, the new, higher result becomes the FCL.
The FCL is also used to determine the Family Emission Limit (FEL), which serves as the emission limit for any subsequent field testing conducted after the time of certification.  This would primarily include selective enforcement audits, but also may include in-use testing for GHGs.  The FEL differs from the FCL in that it includes an EPA-defined compliance margin; which has been defined at 3 percent for the final rule. Our initial proposal included a 2 percent margin based on round-robin testing of the same engine at several laboratories.  Since that time, additional data has indicated that it may be more appropriate to use a 3 percent margin to also account for production variability between engines. Under this final rule, the FEL will always be 3final percent higher than the FCL.
Engine Emission Testing
Under current non-GHG engine emissions regulations, manufacturers are required to demonstrate compliance using two test methods: the heavy-duty transient cycle and the heavy-duty steady state test. Each test is an engine speed versus engine torque schedule intended to be run on an engine dynamometer.  Over each test, emissions are sampled using the equipment and procedures outlined in 40 CFR part 1065, which includes provisions for measuring CO2, N2O, and CH4. Emissions may be sampled continuously or in a batch configuration (commonly known as "bag sampling") and the total mass of emissions over each cycle are normalized by the engine power required to complete the cycle.  Following each test, a validation check is made comparing actual engine speed and torque over the cycle to the commanded values. If these values do not align well, the test is deemed invalid.
The transient Heavy-duty FTP cycle is characteristic of typical urban stop-and-go driving. Also included is a period of more steady state operation that would be typical of short cruise intervals at 45 to 55 miles per hour.  Each transient test consists of two 20 minute tests separated by a "soak" period of 20 minutes.  The first test is run with the engine in a "cold" state, which involves letting the engine cool to ambient conditions either by sitting overnight or by forced cooling provisions outlined in §86.1335-90 (or 40 CFR part 1036).  This portion of the test is meant to assess the ability of the engine to control emissions during the period prior to reaching normal operating temperature. This is commonly a challenging area in criteria pollutant emission control, as cold combustion chamber surfaces tend to inhibit mixing and vaporization of fuel and aftertreatment devices do not tend to function well at low temperatures.
Following the first test, the engine is shut off for a period of 20 minutes, during which emission analyzer checks are performed and preparations are made for the second test (also known as the "hot" test).  After completion of the second test, the results from the cold and hot tests are weighted and a single composite result is calculated for each pollutant.  Based on typical in-use duty cycles, the cold test results are given a 1/7 weighting and the hot test results are given a 6/7 weighting.  Deterioration factors are applied to the final weighted results and the results are then compared to the emission standards.
Prior to 2007, compliance only needed to be demonstrated over the Heavy-duty FTP. However, a number of events brought to light the fact that this transient cycle may not be as well suited for engines which spend much of their duty cycle at steady cruise conditions, such as those used in line-haul semi-trucks.  As a result, the steady-state SET procedure was added, consisting of 13 steady-state modes. During each mode, emissions were sampled for a period of five minutes.  Weighting factors were then applied to each mode and the final weighted results were compared to the emission standards (including deterioration factors).  In addition, emissions at each mode could not exceed the NTE emission limits. Alternatively, manufacturers could run the test as a ramped-modal cycle. In this case, the cycle still consists of the same speed/torque modes, however linear progressions between points are added and instead of weighting factors, each mode is sampled for various amounts of time.  The result is a continuous cycle lasting approximately 40 minutes. With the implementation of part 1065 test procedures in 2010, manufacturers are now required to run the modal test as a ramped-modal cycle. In addition, the order of the speed/torque modes in the ramped-modal cycle have changed for 2010 and later engines.
It is well known that fuel consumption, and therefore CO2 emissions, are highly dependent on the drive cycle over which they are measured.  Steady cruise conditions, such as highway driving, tend to be more efficient, having lower fuel consumption and CO2 emissions.  In contrast, highly transient operation, such as city driving, tends to lead to lower efficiency and therefore higher fuel consumption and CO2 emissions. One example of this is the difference between EPA-measured city and highway fuel economy ratings assigned to all new light-duty passenger vehicles.
For this heavy-duty engine and vehicle proposal, we believe it is important to assess CO2 emissions and fuel consumption over both transient and steady state test cycles, as all vehicles will operate in conditions typical of each cycle at some point in their useful life.  However, due to the drive cycle dependence of CO2 emissions, we do not believe it is reasonable to have a single CO2 standard which must be met for both cycles.  A single CO2 standard would likely prove to be too lax for steady-state conditions while being too strict for transient conditions.  Therefore, the agencies are finalizing that all heavy-duty engines be tested over both transient and steady-state tests.  However, only the results from either the transient or steady-state test cycles would be used to assess compliance with GHG standards, depending on the type of vehicle in which the engine will be used.  Engines that will be used in Class 7 and 8 combination tractors would use the ramped-modal cycle for GHG certification, and engines used in vocational vehicles would use the Heavy-duty FTP cycle.  In both cases, results from the other test cycle would be reported but not used for a compliance decision.  Engines will continue to be required to show criteria pollutant compliance over both cycles, in addition to NTE requirements.
The agencies proposed that manufacturers submit both data sets from the transient test at the time of certification. This includes providing both cold start and hot start transient heavy-duty FTP emissions results, as well as the composite emissions at the time of certification.    The proposed rules also required that manufacturers submit modal data from the ramped-modal cycle test..  This was proposed in an effort to improve the accuracy of the simulation model being used for assessing CO2 and fuel consumption performance and overall engine emissions performance.
However several comments were submitted with concerns that modal data was non-discernable when batch sampling was used for certification testing.  Thus, an additional certification test (or tests) would need to be done using either continuous analyzers or batch sampling at each mode; each option raising the cost and complexity of certification testing.  The agencies agree that (at this time) this raises practical issues for certification testing, however we also believe that manufacturers have significant data from these modal points which could be used to satisfy our model refinement goals. Therefore, we believe it is appropriate to still require the submission of modal data, however manufacturers may submit development data from production-level engine calibrations to satisfy this modal data requirement.
The agencies also recognize that even minor variations in test fuel properties can have an impact on measured CO2 emissions.  Therefore, measured CO2 results are to be corrected using a reference energy content, which is defined in the regulations.  This correction must be performed for each test and each batch of test fuel.  However, manufacturers may develop robust testing procedures that reduce the variation in test fuel properties to within the level of measurement uncertainty of the fuel properties themselves.  If this is the case, an annual review is still necessary to confirm the validity of this constant value.
As explained above in Section II, the agencies are finalizing an alternative standard whereby manufacturers may elect that certain of their engine families meet an alternative percent reduction standard, measured from the engine family's 2011 baseline, instead of the main 2014 MY standard.  As part of the certification process, manufacturers electing this standard would not only have to notify the agency of the election but also demonstrate the derivation of the 2011 baseline CO2 emission level for the engine family.  Manufacturers would also have to demonstrate that they have exhausted all credit opportunities.
Durability testing
Another element of the current certification process is the requirement to complete durability testing to establish DFs. As previously mentioned, manufacturers are required to demonstrate that their engines comply with emission standards throughout the regulatory compliance period of the engine.  This demonstration is commonly made through the combination of low-hour test results and testing based deterioration factors.
For engines without aftertreatment devices, deterioration factors primarily account for engine wear as service is accumulated.  This commonly includes wear of valves, valve seats, and piston rings, all of which reduce in-cylinder pressure. Oil control seals and gaskets also deteriorate with age, leading to higher lubricating oil consumption.  Additionally, flow properties of EGR systems may change as deposits accumulate and therefore alter the mass of EGR inducted into the combustion chamber.  These factors, amongst others, may serve to reduce power, increase fuel consumption, and change combustion properties; all of which affect pollutant emissions.
For engines equipped with aftertreatment devices, DFs take into account engine deterioration, as described above, in addition to aging affects on the aftertreatment devices.  Oxidation catalysts and other catalytic devices rely on active precious metals to effectively convert and reduce harmful pollutants. These metals may become less active with age and therefore pollutant conversion efficiencies may decrease.  Particulate filters may also experience reduced trapping efficiency with age due to ash accumulation and/or degradation of the filter substrate, which may lead to higher tailpipe PM measurements and/or increased regeneration frequency. If a pollutant is predominantly controlled by aftertreatment, deterioration of emission control depends on the continued operation of the aftertreatment device much more so than on consistent engine-out emissions.
At this time, we anticipate that most engine component wear will not have a significant negative impact on CO2 emissions. However, wear and aging of aftertreatment devices may or may not have a significant negative impact on CO2 emissions.  In addition, future engine or aftertreatment technologies may experience significant deterioration in CO2 emissions performance over the useful life of the engine.  For these reasons, we believe that the use of DFs for CO2 emissions is both appropriate and necessary. As with criteria pollutant emissions, these DFs are preferably developed through testing the engine over a representative duty cycle for an extended period of time. This is typically either half or full useful life, depending on the regulatory class. The DFs are then calculated by comparing the high-hour to low-hour emission levels, either by division or subtraction (for multiplicative & additive DFs, respectively).
This testing process may be a significant cost to an engine manufacturer, mainly due to the amount of time and resources required to run the engine out to half or full useful life.  For this reason, durability testing for the determination of DFs is not commonly repeated from model year to model year. In addition, some DFs may be allowed to carry over between families sharing a common architecture and aftertreatment system.  EPA prefers to have manufacturers develop testing-based DFs for their products. However, we do understand that for the reasons stated above, it may be impractical to expect manufacturers to have testing-based deterioration factors available for these  final rules. Therefore, we are allowing manufacturers to use EPA-assigned DFs for CO2.   However, we also understand that CO2 is traditionally measured as part of normal engine dynamometer testing. Therefore, we are requiring that manufacturers include CO2 data over their criteria pollutant durability demonstrations (if available), which will aid the agency in developing more accurate assigned DFs.
IRAFs/Regeneration Impacts on CO2
Heavy-duty engines may be equipped with exhaust aftertreatment devices which require periodic "regeneration" to return the device to a nominal state. A common example is a diesel particulate filter, which accumulates PM as the engine is operated.  When the PM accumulation reaches a threshold such that exhaust backpressure is significantly increased, exhaust temperature is actively increased to oxidize the stored PM.  The increase in exhaust temperature is commonly facilitated through late combustion phasing and/or raw fuel injection into the exhaust system upstream of the filter.  Both methods impact emissions and therefore must be accounted for at the time of certification. In accordance with §86.004-28(i), this type of event would be considered infrequent because in most cases they only occur once every 30 to 50 hours of engine operation (rather than once per transient test cycle), and therefore adjustment factors must be applied at certification to account for these effects.
Similar to DFs, these adjustment factors are based off of manufacturer testing; however this testing is far less time consuming.  Emission results are measured from two test cycles: with and without regeneration occurring.  The differences in emission results are used, along with the frequency at which regeneration is expected to occur, to develop upward and downward adjustment factors. Upward adjustment factors are added to all emission results derived from a test cycle in which regeneration did not occur. Similarly, downward adjustment factors are subtracted from results based on a cycle which did experience a regeneration event.  Each pollutant will have a unique set of adjustment factors and additionally, separate factors are commonly developed for transient and steady-state test cycles.
The impact of regeneration events on criteria pollutants varies by pollutant and the aftertreatment device(s) used. In general, the adjustment factor can have a very significant impact on compliance with the NOX standard.  For this reason, heavy-duty vehicle and engine manufacturers are already very well motivated to extend the regeneration frequency to as long an interval as possible and to reduce the during of the regeneration as much as possible.  Both of these actions significantly reduce the impact of regeneration on CO2 emissions and fuel consumption.  We do not believe that adding an adjustment factor for infrequent regeneration to the CO2 or fuel efficiency standards would provide a significant additional motivation for manufacturers to reduce regenerations.  Moreover, doing so would add significant and unnecessary uncertainty to our projections of CO2 and fuel consumption performance in 2014 and beyond.  In addressing that uncertainty, the agencies would have to set less stringent fuel efficiency and CO2 standards for heavy-duty trucks and engines.  Therefore, we are not  requiring the use of infrequent regeneration adjustment factors for CO2 or fuel efficiency in this program.
Auxiliary Emission Control Devices
As part of the engine control strategy, there may be devices or algorithms which reduce the effectiveness of emission control systems under certain limited circumstances. These strategies are referred to as Auxiliary Emission Control Devices (AECDs). One example would be the reduced use of EGR during cold engine operation. In this case, low coolant temperatures may cause the electronic control unit to reduce EGR flow to improve combustion stability.  Once the engine warms up, normal EGR rates are resumed and full NOX control is achieved.
At the time of certification, manufacturers are required to disclose all AECDs and provide a full explanation of when the AECD is active, which sensor inputs effect AECD activation, and what aspect of the emission control system is affected by the AECD.  Manufacturers are further required to attest that their AECDs are not "defeat-devices," which are intentionally targeted at reducing emission control effectiveness.
Several common AECDs disclosed for criteria pollutant certification will have a similarly negative influence on GHG emissions as well.  One such example is cold-start enrichment, with provides additional fueling to stabilize combustion shortly after initially starting the engine.  From a criteria pollutant perspective, HC emissions can reasonably be expected to increase as a result. From a GHG perspective, the extra fuel does not result in a similar increase in power output and therefore the efficiency of the engine is reduced, which has a negative impact on CO2 emissions. In addition, there may be AECDs that uniquely reduce GHG emission control effectiveness.  Therefore, consistent with today's certification procedures, we are finalizing that a comprehensive list of AECDs covering both criteria pollutant, as well as GHG emissions is required at the time of certification.
EPA's N2O and CH4 Standards
In 2009, EPA issued rules requiring manufacturers of mobile-source engines to report the emissions of CO2, N2O, and CH4 (74 FR 56260, October 30, 2009). While CO2 is commonly measured during certification testing, CH4 and N2O are not.  CH4 has traditionally not been included in criteria pollutant regulations because it is a relatively stable molecule and does not contribute significantly to ground-level ozone formation.  In addition, N2O is commonly a byproduct of lean-NOX aftertreatment systems. Until recently, these types of systems were not widely used on heavy-duty engines and therefore N2O emissions were insignificant.  Both species, while emitted in small quantities relative to CO2, have much higher global warming potential than CO2 and therefore must be considered as part of a comprehensive GHG regulation.
EPA is  requiring that CH4 and N2O be reported at the time of certification, however we will allow manufacturers to submit  a compliance statement based on good engineering judgment for the first year of the program in lieu of direct measurement of N2O.  However, beginning in the 2015 model year, the agency is  requiring the direct measurement of N2O for certification.  The intent of the CH4 and N2O standards are more focused on prevention of future increases in these compounds, rather than forcing technologies that reduce these pollutants.  As one example, we envision manufacturers satisfying this requirement by continuing to use catalyst designs and formulations that appropriately control N2O emissions rather than pursuing a catalyst that may increase N2O.  In many ways this becomes a design-based criterion in that the decision of one catalyst over another will effectively determine compliance with N2O standards over the useful life of the engine.
Since catalytic activity generally changes with age and service accumulation, it is not unreasonable to expect changes in N2O and CH4 emissions over the useful life of the engine. We also believe that low-hour test results coupled with deterioration factors provides an adequate representation of end-of-life emission levels for these pollutants. However, the requirement to measure N2O and CH4 during testing is relatively new and we do not expect that manufacturers have consistent durability data to formulate deterioration factors for these final rules. We also do not believe it is appropriate to require all new durability testing to satisfy this requirement, as this would result in a nontrivial burden to engine manufacturers.  Instead we will be assigning deterioration factors for N2O and CH4 for this rule.  If the use of assigned deterioration factors jeopardizes compliance with the emission standards, we will also allow manufacturers to propose unique testing-based deterioration factors for these pollutants.
Additional Compliance Provisions
Warranty & Defect Reporting
Under section 207 of the CAA, engine manufacturers are required to warrant that their product is free from defects that would cause the engine to not comply with emission standards.  This warranty must be applicable from when the engine is introduced into commerce through a period generally defined as half of the regulatory useful life (specified in hours and years, whichever comes first).  The exact time of this warranty is dependent on the regulatory class of the engine.  In addition, components that are considered "high cost" are required to have an extended warranty. Examples of such components would be exhaust aftertreatment devices and electronic control units.
Current warranty provisions in 40 CFR part 86 define the warranty periods and covered components for heavy-duty engines. The current list of components is comprised of any device or system whose failure would result in an increase in criteria pollutant emissions.  We remain convinced that this list  is adequate for addressing GHG emissions as well, based on comments received from the proposed rules.   The following list identifies items commonly defined as critical emission-related components:
Electronic control units
Aftertreatment devices
Fuel metering components
EGR-System components
Crankcase-ventilation valves
All components related to charge-air compression and cooling
All sensors and actuators associated with any of these components

When a manufacturer experiences an elevated rate of failure of an emission control device, they are required to submit defect reports to the EPA. These reports will generally have an explanation of what is failing, the rate of failure, and any possible corrections taken by the manufacturer. Based on how successful EPA believes the manufacturer to be in addressing these failures, the manufacturer may need to conduct a product recall.  In such an instance, the manufacturer is responsible for contacting all customers with affected units and repairing the defect at no cost to them.  We believe this structure for the reporting of criteria pollutant defects, and recalls, is appropriate for components related to complying with GHG emissions as well.
Maintenance
Engine manufacturers are required to outline maintenance schedules that ensure their product will remain in compliance with emission standards throughout the useful life of the engine.  This schedule is required to be submitted as part of the application for certification. Maintenance that is deemed to be critical to ensuring compliance with emission standards is classified as "critical emission-related maintenance." Generally, manufacturers are discouraged from specifying that critical emission-related maintenance is needed within the regulatory useful life of the engine. However, if such maintenance is unavoidable, manufacturers must have a reasonable basis for ensuring it is performed at the correct time. This may demonstrated through several methods including survey data indicating that at least 80% of engines receive the required maintenance in-use or manufacturers may provide the maintenance at no charge to the user.  During durability testing of the engine, manufacturers are required to follow their specified maintenance schedule.
Maintenance relating to components relating to reduction of GHG emissions are not expected to present unique challenges. Therefore, we are not finalizing any changes to the provisions for the specification of emission-related maintenance as outlined in 40 CFR part 86.
 Enforcement Provisions
Emission Control Information Labels
Current provisions for engine certification require manufacturers to equip their product with permanent emission control information labels.  These labels list important characteristics, parameters, and specifications related to the emissions performance of the engine.  These include, but are not limited to, the manufacturer, model, displacement, emission control systems, and tune-up specifications. In addition, this label also provides a means for identifying the engine family name, which can then be referenced back to certification documents.  This label provides essential information for field inspectors to determine that an engine is in fact in the certified configuration.
We do not anticipate any major changes needing to be made to emission control information labels as a result of new GHG standards and a single label is appropriate for both criteria pollutant and GHG emissions purposes.  Perhaps the most significant addition will be the inclusion of Family Certification Levels or Family Emission Limits for GHG pollutants, if the manufacturer is participating in averaging, banking, and trading.  In addition, the label will need to indicate whether the engine is certified for use in vocational vehicles, tractors, or both.
In-Use Standards
In-use testing of engines provides a number of benefits for ensuring useful life compliance.  In addition to verifying compliance with emission standards at any given point in the useful life, it can be used along with manufacturer defect reporting, to indentify components failing at a higher than normal rate. In this case, a product recall or other service campaign can be initiated and the problem can be rectified. Another key benefit of in-use testing is the discouragement of control strategies catered to the certification test cycles.  In the past, engine manufacturers were found to be producing engines that performed acceptably over the certification test cycle, while changing to alternate operating strategies "off-cycle" which caused increases in criteria pollutant emissions.  While these strategies are clearly considered defeat devices, in-use testing provides a meaningful way of ensuring that such strategies are not active under normal engine operation.
Currently, manufacturers of certified heavy-duty engines are required to conduct in-use testing programs. The intent of these programs is to ensure that their products are continuing to meet criteria pollutant emission standards at various points within the useful life of the engine.  Since initial certification is based on engine dynamometer testing, and removing in-use engines from their respective vehicles is often impractical, a unique testing procedure was developed. This includes using portable emission measurement systems (PEMS) and testing the engine over typical in-situ drive routes rather than a prescribed test cycle. To assess compliance, emission results from a well defined area of the speed/torque map of the engine, known as the NTE zone, are compared to the emission standards.  To account for potential increases in measurement and operational variability, certain allowances are applied to the standard which results in the standard for NTE measurements (NTE limit) to be at or above the duty cycle emission standards.
In addition, EPA also conducts an annual in-use testing program of heavy-duty engines.  Testing procured vehicles with specific engines over well-defined drive routes using a constant trailer load allows for a consistent comparison of in-use emissions performance.  If potential problems are identified in-situ, the engine may be removed from the vehicle and tested using an engine dynamometer over the certification test cycles. If deficiencies are confirmed the agency will either work with the manufacturer to take corrective action or proceed with enforcement action against the manufacturer.
The GHG reporting rule requires manufacturers to submit CO2 data from all engine testing (beginning in the 2011 model year), which we believe is equally applicable to in-use measurements. Methods of CO2 in-situ measurement are well established and most, if not all, PEMS devices measure and record CO2 along with criteria pollutants.  CH4 and N2O present in-situ measurement challenges that may be impractical to overcome for this testing, and therefore it is not recommended that they be included in in-use testing requirements at this time.  While measurement of CO2 may be practical and important, implementing an NTE emission standard for CO2 is challenging.  As previously discussed, CO2 emissions are highly dependent on the drive cycle of the vehicle, which does not lend itself well to the NTE-based test procedure. Therefore, we propose that manufacturers be required to submit CO2 data from in-situ testing, in both g/bhp-hr and g/ton-mile, but these data will be used for reference purposes only (there would be no NTE limit/standard for CO2).  For engine-based (dynamometer) in-use testing, compliance with CO2 emission standards will be judged off of the FCL of the engine family.
Other Certification Provisions
Carryover/Carry Across Certification Test Data
EPA's current certification program for heavy-duty engines allows manufacturers to carry certification test data over and across certification testing from one model year to the next, when no significant changes to models are made. EPA will also apply this policy to CO2, N2O and CH4 certification test data.
Certification Fees
The CAA allows EPA to collect fees to cover the costs of issuing certificates of conformity for the classes of engines covered by this proposal. On May 11, 2004, EPA updated its fees regulation based on a study of the costs associated with its motor vehicle and engine compliance program (69 FR 51402). At the time that cost study was conducted, the current rulemaking was not considered. At this time the extent of any added costs to EPA as a result of this proposal is not known. EPA will assess its compliance testing and other activities associated with the rule and may amend its fees regulations in the future to include any warranted new costs.
Onboard Diagnostics
Beginning with the 2010 model year, manufacturers have been phasing in on-board diagnostic systems (OBD) on heavy-duty engines pursuant to the heavy-duty OBD rulemaking finalized by the EPA in 2009.  These systems monitor the activity of the emission control system and issue alerts when faults are detected.  These diagnostic systems are currently being developed based around components and systems that influence criteria pollutant emissions.  Consistent with the light-duty vehicle GHG rule, we believe that monitoring of these components and systems for criteria pollutant emissions will have an equally beneficial effect on CO2 emissions.  Therefore, we have not finalized any additional unique onboard diagnostic provisions for heavy-duty GHG emissions.  The proposal for this action also did not propose new or different diagnostic requirements from those finalized in the previous action taken by EPA.
The Agencies received comments from engine manufacturers, hybrid system manufacturers, and related trade groups which broached concerns regarding the feasibility of applying on-board diagnostics to hybrid applications starting in 2013 and requested a delay until 2020 with a phase-in of enforcement liability starting that same year.  In response to the comments that the agencies should consider delaying implementation of the provisions of a separate action to facilitate introduction of hybrid technology, the agencies are taking an approach that is consistent with certain provisions of the existing final action for heavy-duty OBD.  To that end, manufacturers who certify hybrid systems will continue to have the responsibility of implementing compliant diagnostic systems, however, we are extending the OBD phase-in for engines with hybrid systems only to allow time for them to be able to address communication protocol development concerns (e.g. SAE J1939), component development concerns (e.g. hardware and software), service information (e.g. service website availability), diagnostic communication with generic scantools, etc., and to address the availability of heavy-duty OBD compliant engines with sufficient lead-time for additional hybrid diagnostic system development given resource constraints as engine manufacturers are focused on meeting the 2013 requirements for conventional products at this time.
Hybrid manufacturers have indicated that the interaction between hybrid systems and OBD compliant engines are not well understood at this time, for example if the system shuts down the vehicle at idle, the idle diagnostics cannot run.  In addition, there are many different hybrid systems being developed which make much of this technology both immature and low volume, engine manufacturers are concerned that this would result in high costs due to frequent design changes that could result as this technology develops and have asked for flexibility for unique hybrid applications.  Consistent with the Agencies goals to incentivize the development of hybrid designs (systems designed to capture wasted energy and reuse fuel consumption) we are allowing hybrid manufacturers time to develop their systems while simultaneously  developing the capability to meet HD OBD requirements.
Communication protocol development is an integral part of developing hybrid OBD capability for the heavy-duty industry which is not vertically integrated.  There are different protocols required to be used for OBD communication in a vehicle depending on the type of engine (gasoline or diesel).  These protocols are developed in part to standardize the transmission of electronic signals and control information among vehicle components.  The J1939 communication protocol is developed by committee through SAE and is required for use with diesel engines.  Messages sent through a J1939 network contain a series of information (e.g. an identifier, message priority, data, etc.) and these parameters must be agreed upon through the SAE committee and tailored such that they work for all manufacturers and as such. Development of this communication protocol and criteria for the messages can take a substantial amount of time.  Hybrid manufacturers have stated that until such time as a `plug and play scheme' is available, hybrid volumes will not be able to increase significantly.  At this time, there are only a few such messages that have been developed for use in hybrid systems, and there is much additional development needs to take place.  The type of messages needed must first be identified once 2013 HDOBD compliant engines are available for use in HD hybrid OBD system development.  After needed messages are identified, the content of each message must be developed and agreed upon through a ballot process.  Manufacturers have stated that this will be an iterative process that will likely take at least X years to completely develop the protocol for use with the different variations of hybrid systems and architectures, different types of energy storage systems, and for systems used in the wide variety of applications in the heavy-duty market, and we agree with this assessment.  While we recognize that a level of communication exists today between engines and transmissions for this industry, the level of control and impact on engine system operation becomes much more significant once hybrid technology is introduced.  The purpose of the hybrid energy system is to supplement overall vehicle power demands.  As such, the methods used for integrating the energy from the hybrid system into overall vehicle operation vary from allowing additional internal combustion engine lower power operation to potentially decreasing the amount of engine "on" time.  This range of performance impacts will serve to reduce GHG emissions by reducing demands on the engine.  Existing transmission systems and other powertrain components do not exercise the level of control the hybrid will need to exercise to effectively reduce GHG emissions and improve fuel consumption performance for internal combustion engines.
Component development concerns raised by hybrid manufacturers include both changes that may be required to software and/or hardware systems on both existing hybrid products and on hybrid systems currently under development.  Software systems in existing products have been developed to provide proprietary diagnostic capability (as no standardized system such as J1939 had been developed for these systems), however, these software systems are not OBD complaint.  These products will likely have to have entirely new software systems developed for them which may result in hardware changes as well.  Manufacturers have stated that a complete software system can take up to X years to develop and X to validate.  Hardware may also need to be changed to accommodate OBD on hybrid systems, in particular, affecting current production systems which may not have controllers that can support full OBD.  The low volume sales and high cost of a controller program (which can reach in the X of dollars) cannot support a hardware change for hybrids alone, rather, existing hybrid systems will have to wait until such a hardware upgrade is planned for other reasons.  In addition, new hardware programs, such as developing a new ECU can take X years.  While it is possible for some of this work to be done concurrently, how much can be done this way is dependent on the configuration of each individual system.  In addition, manufacturers may have contractual agreements with hardware and software suppliers that will have to be reconfigured to address a complete OBD program.
Hybrid manufacturers have stated that they will be unable to produce hybrid systems that will be OBD complaint in 2013.  Given the concerns discussed above and the general lack of availability of OBD compliant engines until the completion of the HD OBD phase-in, the Agencies have determined that to require manufacturers of systems that depend on the availability of the OBD compliant engines to then be able to immediately implement additional requirements may be impractical in many instances.  Given the phase-in HD OBD that already exists however, we do not believe a delay to 2019 or 2020 is warranted.  While not all of the engines that would potentially have hybrid systems incorporated into their design are available in their final OBD configuration at the time of this action, it is clear that some engine systems will be available.  Additionally, there is an expectation that engine manufacturers, their suppliers and customers will have to continue to work cooperatively to deliver products for the market.  This cooperation must include a level of concurrent engineering prior to products being brought to market.  At this time we believe a delay to 2016 for the phase-in of OBD for heavy-duty engines equipped with hybrid systems should provide the requisite lead time from the date of this action to the date of implementation provides adequate time for development of components and protocols necessary for successful integration of complete OBD systems for engines equipped with hybrid systems.
Manufacturers will be required to implement feasible controls for these hybrid systems that do not adversely impact emissions performance in 2013 and by 2016-17 more fully developed OBD systems will need to be applied to certified engine system configurations.  The phase in period takes into account that current production systems are likely to be smaller in terms of sales volume than newly developed systems, and may require more hardware and software development as some of these systems have been in production for nearly a decade and have developed proprietary system diagnostic capability that does not meet OBD requirements, and provides them an additional year of time to comply with the heavy-duty OBD regulations.  Hybrid systems put into production after the publication of this final rulemaking would be required to meet the 2009 heavy-duty OBD requirements in 2016 consistent with the next phase-in date for heavy-duty OBD, while those hybrid systems already in production as of the publication of this final rulemaking have until 2017 to be compliant with these OBD requirements.
In the interim, engine system diagnostics must meet CARB's Engine Manufacturer Diagnostic Systems Requirements (EMD) including system monitoring requirements for NOX aftertreatment, fuel systems, exhaust gas recirculation, particulate matter traps, and emission-related electronic components.  In addition, these systems must maintain existing OBD capability and calibrations for certified engines used in hybrid applications with the exception of having liability for failure to meet diagnostic performance requirements (e.g. detection thresholds).  Hybrid systems must also continue to maintain existing diagnostic capability to ensure proper function consistent with the performance for which the hybrid system is certified as well as, safe operation of the hybrid system.
Applicability of Current High Altitude Provisions to Greenhouse Gases
EPA is requiringfinalizing that engines covered by this proposal must meet CO2, N2O and CH4 standards at elevated altitudes. The CAA requires emission standards under section 202 for heavy-duty engines to apply at all altitudes.  EPA does not expect engine CO2, CH4, or N2O emissions to be significantly different at high altitudes based on engine calibrations commonly used at all altitudes. Therefore, EPA will retain its current high altitude regulations so manufacturers will not normally be required to submit engine CO2 test data for high altitude. Instead, they will be required to submit an engineering evaluation indicating that common calibration approaches will be utilized at high altitude. Any deviation in emission control practices employed only at altitude will need to be included in the AECD descriptions submitted by manufacturers at certification. In addition, any AECD specific to high altitude will be required to include emissions data to allow EPA evaluate and quantify any emission impact and validity of the AECD.
Emission-Related Installation Instructions
Engine manufacturers are currently required to provide detailed installation instructions to vehicle manufacturers.  These instructions outline how to properly install the engine, aftertreatment, and other supporting systems, such that the engine will operate in its certified configuration. At the time of certification, manufacturers may be required to submit these instructions to EPA to verify that sufficient detail has been provided to the vehicle manufacturer.
We do not anticipate any major changes to this documentation as a result of regulating GHG emissions. The most significant impact will be the addition of language prohibiting vehicle manufacturers from installing engines into vehicle categories in which they are not certified for. An example would be a tractor manufacturer installing an engine certified for only vocational vehicle use.  Explicit instructions on behalf of the engine manufacturer that such acts are prohibited will serve as sufficient notice to the vehicle manufacturers and failure to follow such instructions will in the vehicle manufacturer being in non-compliance.
Alternate CO2 Emission and Fuel Consumption Standards
Under the final rule, engine manufacturers have the option of certifying to alternate CO2 emission and fuel consumption standards for model years 2014 through 2016.  These alternate standards are defined as6 5 percent below a baseline value established from their corresponding 2011 model-year products.  If a manufacturer elects to participate in this program they must indicate this on their certification application. In addition, sufficient details must be submitted regarding the baseline engine such that the agency can verify that the correct optional CO2 emission and fuel consumption standards have been calculated.  This data will need to include the engine family name of the baseline engine, so references to the original certification application can be made, as well as test data showing the CO2 emissions and fuel consumption of the baseline engine.
Compliance Reports
	Early Model Year Data
NHTSA's regulatory text in the NPRM included specifications for manufacturers to submit pre-certification compliance reports for heavy duty engines.   The pre-certification reports included requirements for manufactures to submit information to identify the types of engines, expected test results, production volumes and credits.  The reporting requirements were general in nature despite having an existing emissions program for heavy duty engines.  The existing ABT program for NOx and PM emissions for heavy-duty engines has existed since 2001 (see 66 FR 5002 signed on January 18, 2001) but does not require reporting early model year compliance information.  The agencies sought comments on the report provisions in the NPRM but commenters failed to offer recommendations on what content should be required. As a result, the agencies have decided to eliminate the pre-certification report because engine manufacturers have no experience in providing GHG information and the proposed information may not be available until subsequent model years.  For the next phase of this GHG program, the agencies may adopt a pre-model year report for engines.
As an alternative to receiving early compliance model year information in the precertification reports, the agencies have decided to use manufacturer's application for certificates of conformity to obtain early model estimates.  Currently, the applications for certificates are not required to include the fuel consumption information required by NHTSA.  Therefore, the agencies are adopting provisions in the final rule for manufacturers to provide emission and equivalent fuel consumption estimates in the manufacturer's applications for certification.  The agencies will treat information submitted in the applications as a manufacturer's demonstration of providing early compliance information, similar to the pre-model year report submitted for heavy-duty pick trucks and vans.   The final rule establishes a harmonized approach by which manufacturers will submit applications through the EPA VERIFY database system as the single point of entry for all information required for this national program and both agencies will have access to the information.  If by model year 2012, the agencies are not prepared to receive information through the EPA VERIFY database system, manufacturers are expected to submit written applications to the agencies.   This approach should streamline this process and reduce industry burden and provide sufficient information for the agency's to carry out their early compliance activities.
Final Reports
For engines, the NPRM proposed for manufacturers to submit EOY reports and final reports.  An EOY report for manufacturers using the ABT program was required to be submitted no later than 90 days after the calendar year and final report no later than 270 days after the calendar year.  Manufacturers not participating in the ABT program were required to provide an EOY report within 45 days after the calendar year but no final reports were required.  The final ABT report due was established coinciding with EPA's existing criteria pollutant report for heavy-duty engines complying with NOx and PM standards.  Similar to that program, the proposed EOY and final reports required receiving engine type designation, engine family and credit plans for engine manufacturers.
In response to the NPRM, there were no comments received on the final reports for engines.  For the final rule, the agencies will retain the NPRM proposal for the EOY and final reports.  However, the agencies will consolidate the reporting as done for other vehicle categories and will require emissions and equivalent fuel consumption information to be submitted to EPA. The final rule establishes a harmonized approach by which manufacturers will submit applications to EPA the as the single point of entry for all information required for this national program and both agencies will have access to the appropriate information.  If by model year 2012, the agencies are not prepared to receive information through a database system, manufacturers are expected to submit written applications to the agencies.  The agencies are also combining the EOY reports for manufacturers not using ABT to provide a product volume report due 90 days after the end of the model year and the ABT report required 90 days after the model year.  A summary of the required information in the final rule for EOY and final reports is as follows:
         * Engine family designation and averaging set.
         * Engine emissions and fuel consumption standards including any alternative standards used
         * Engine family FCLs.
         * Final production volumes
         * Certified test cycles
         * Useful life values for engine families
         * A credit plan identifying the manufacturers actual credit balances, credit flexibilities, credit trades and a credit deficit plan if needed demonstrating how it plans to resolve any credit deficits that might occur for a model year within a period of up to three model years after that deficit has occurred
 Additional Required Information
Throughout the model year, manufacturers will be required to submit various submissions to the agencies to comply with various aspects of the rule.  These requests have differing criteria for submission and approval.  Table V-1 below provides a summary of the types of submission, required submission dates and the EPA and NHTSA regulations that apply.
The agencies will review and grant any requests considering the timeliness of the submissions and the completeness of the requests.
Table V-1: Summary of Required Information for Compliance

Class 7 and 8 Combination Tractors
 Compliance Approach
In addition to requiring engine manufacturers to certify their engines, manufacturers of Class 7 and 8 combination tractors must also certify that their vehicles meet the  CO2 emission and fuel consumption standards.  This vehicle certification will ensure that efforts beyond just engine efficiency improvements are undertaken to reduce GHG emissions and fuel consumption.  Some examples include aerodynamic improvements, rolling resistance reduction, idle reduction technologies, and vehicle speed limiting systems.
Unlike engine certification however, this certification would be based on a load-specific basis (g/ton-mile or gal/1,000 ton-mile as opposed to work-based, or g/bhp-hr). This would take into account the anticipated vehicle loading that would be experienced in use and the associated affects on fuel consumption and CO2 emissions. Vehicle manufacturers would also be required to warrant their products against emission control system defects, and demonstrate that a service network is in place to correct any such conditions.  The vehicle manufacturer also bears responsibility in the event that an emission-related recall is necessary.
Certification Process
In order to obtain a certificate of conformity for the tractor, vehicle manufacturers would complete a compliance demonstration, showing that their product meets emission standards as well as other regulatory requirements.  For purposes of this demonstration, vehicles with similar emission characteristics throughout their useful life are grouped together in vehicle families, which are defined primarily by the regulatory subclass of the vehicle  Manufacturers may further classify vehicles together into sub-families within a given vehicle family. Examples of characteristics that would define a vehicle sub-family for heavy-duty vehicles are wheel and tire package, aerodynamic profile, tire rolling resistance, and vehicle speed limiting system.  Compliance with the emission standards (or FEL) will be determined at the sub-family level.
Under this system, the worst-case vehicle configuration would be selected based on having the highest fuel consumption, and all other configurations within the family or sub-family are assumed to have emissions and fuel consumption at or below the parent model and therefore in compliance with CO2 emission and fuel consumption standards.  Any vehicle within the family can be subject to selective enforcement auditing in addition to confirmatory or other administrator testing.
We anticipate vehicle families for Class 7 and 8 combination tractors to utilize the standardized 12-digit naming convention, as outlined in the engine certification section of this chapter.  As with engines, each certifying vehicle manufacturer will have a unique three digit code assigned to them.  Currently, there is no 5[th] digit (industry sector) code for this class of vehicles, for which we propose to use the next available character, "2." Since we are finalizing that the engine is one of several family defining features, we still believe it is appropriate to include engine displacement in the family name. If the test-group consists includes multiple engine models with varying displacements, the largest would be specified in the vehicle family name, consistent with current practices.   The remaining characters would remain available for California ARB and/or manufacturer use, such that the result is a unique vehicle family name.
Class 7 and 8 tractors share several common traits, such as the trailer attachment provisions, number of wheels, and general construction. However, further inspection reveals key differences related to GHG emissions.  Payloads hauled by Class 7 tractors are significantly less than Class 8 tractors. In addition, Class 8 vehicles may have provisions for hoteling ("sleeper cabs"), which results in an increase in size as well as the addition of comfort features like power and climate control for use while the truck is parked.   Both segments may have various degrees of roof fairing to provide better aerodynamic matching to the trailer being pulled. This is a feature which can help reduce CO2 emissions significantly when properly matched to the trailer, but can also increase CO2 emissions if improperly matched.  Based on these differences, it is reasonable to expect differences in CO2 emissions, and therefore these properties form the basis for the final combination tractor regulatory subcategories.
The various combinations of payload, cab size, and roof profile result in eight final regulatory subcategories for Class 7 and 8 tractors.  Class 7 tractors are divided into two regulatory subcategories: one for low and mid roof height profiles, and one for high roof profiles. Both Class 7 subcategories is subject to a 10 year, 185,000 regulatory useful life.  Class 8 tractors are split into six regulatory subcategories reflecting two cab sizes (day and sleeper) and three roof height profiles (low, mid, and high).  All Class 8 tractors are subject to a 10 year, 435,000 mile regulatory useful life.final
Demonstrating Compliance With the Final Standards
CO2 and Fuel Consumption Standards
Consistent with existing certification processes for light-duty vehicles and heavy-duty pickups and vans, emissions testing of the complete vehicle would be the preferred method for demonstrating compliance with vehicle emission standards.  However, vehicle-level certification is new to the heavy-duty vehicle segment above 14,000 lb.  Therefore, most vehicle manufacturers are not adequately equipped to conduct vehicle-level emission testing for Class 7 and 8 combination tractors.  Chassis dynamometers, emission sampling equipment, and staff engineering support are a few of the factors that would add significant cost to vehicle development in a relatively short amount of time, which may make the prospect of vehicle testing quite onerous.  In addition to the infrastructure and testing facilities the industry would need to add, the agencies have not completed the extensive work ultimately desirable for us to propose new test procedures and standards based on the use of a chassis test procedure. Moreover, as explained in Section II.C, because of the enormous numbers of truck configurations that have an impact on fuel consumption, we do not believe that it would be reasonable, at least initially, to require testing of many combinations of tractor model configurations on a chassis dynamometer.  Recognizing these constraints related to time, staffing, and capitol, we are  requiring only a vehicle simulation model option for demonstrating compliance at the time of certification.  However, we do believe that a chassis based test procedure as currently utilized for vehicles below 14,000 pounds could be a better long-term approach to regulate all heavy-duty vehicles and we will be working towards this goal for future rulemaking efforts.
Model
Vehicle modeling will be conducted using the agencies' simulation model, GEM, which is described in detail in Chapter 4 of the RIA. Basically, this model functions by defining a vehicle configuration and then exercises the model over various drive cycles.  Several initialization files are needed to define a vehicle, which include mechanical attributes, control algorithms, and driver inputs.  The majority of these inputs will be predetermined by EPA and NHTSA for the purposes of vehicle certification.  The net results from GEM are weighted CO2 emissions and fuel consumption values over the drive cycles.  The CO2 emission result will be used for demonstrating compliance with vehicle CO2 standards while the fuel consumption result will be used for demonstrating compliance with the fuel consumption standards.
The vehicle manufacturer will be responsible for entering up to seven inputs relating to the GHG performance of a vehicle configuration although, depending on the regulatory class, fewer inputs may be required.  These inputs include the regulatory class, coefficient of drag, steer tire rolling resistance, drive tire rolling resistance, vehicle speed limit, vehicle weight reduction, and idle reduction credit.  For GEM inputs relating to aerodynamics, the agencies have finalized lookup tables for frontal area and coefficient of drag based on typical performance levels across the industry. Manufacturers are responsible for assessing the aerodynamic performance of their vehicles through testing or a combination of testing and modeling. This test data is then used to select the most appropriate agency-defined bin for entry into GEM.
Tire rolling resistance is simply the measured rolling resistance of the tire in kg per metric ton as described in ISO 28580:2009.  This measured value is expected to be the result of three repeat measurements of three different tires of a given design, giving a total of nine data points.  It is the average of these nine results that will be entered into GEM.  Tire rolling resistance may be determined by either the vehicle or tire manufacturer. In the latter case, a signed statement from the tire manufacturer confirming testing was conducted in accordance with this part is required.
As previously described, limiting vehicle speed can have a significant effect on fuel consumption and we believe that manufacturers should be recognized for including technology that facilitates these limits.  Also as described, these vehicle speed limiters are not likely to be a simple device with a fixed top speed.  "Soft" limits based on driver behavior and limit expiration dates (or mileage) are two of the most common scenarios.  To properly assess the GHG and fuel consumption benefits in light of these features, we are defining the proper methodology for entering the vehicle speed limit into GEM. This is based on an equation including terms for VSL expiration (expiration factor) and VSL soft-top (soft-top factor and soft-top VSL). The result will be an effective vehicle speed limit reflecting the expected mileage and time that the limit will be used for.  Additional details regarding this equation and its derivation can be found in RIA chapter 2.
For vehicle weight reduction, the agencies are primarily addressing the reduction of weight and perhaps number of wheels.  This reduction is assessed relative to a standard combination tractor configuration with dual-wide rear tires with conventional steel wheels.  Manufacturers may elect to use single-wide rear tires/wheels and/or aluminum (or light-weight aluminum) wheels to reduce the weight of their vehicles.  The agencies have defined standard weight reduction levels associated with each combination for entry into GEM.  These reductions are listed in pounds per tire or wheel, so manufacturers will need to multiply this reduction by the number of affected wheels for their total GEM entry.
Manufacturers electing to limit idle time to 300 seconds or less can claim a GHG benefit of 5 g/ton-mile and should be entered into GEM as such.  This benefit cannot be scaled to reflect shorter or longer allowed idle times.
The agencies will enter the appropriate engine map reflecting use of a certified engine in the truck (and will enter the same value even if an engine family is certified to the temporary percent reduction alternative standard, in order to evaluate vehicle performance independently of engine performance.)  We believe this approach reduces the testing burden placed upon manufacturers, yet adequately assesses improvements associated with select technologies.  The model will be publicly available and will be found on EPA's website.
The agency reserves the right to independently evaluate the inputs to the model by way of Administrator testing to validate those model inputs.  The agency also reserves the right to evaluate vehicle performance using the inputs to the model provided by the manufacturer to confirm the performance of the system using GEM. This could include generating emissions results using the GEM and the inputs as provided by the manufacturer based on the agency's own runs.  This could also include conducting comparable testing to verify the inputs provided by the manufacturer.  In the event of such testing or evaluation, the Administrator's results become the official certification results. The exception being that the manufacturer may continue to use their data as initially submitted, provided it represents a worst-case condition over the Administrator's results.
To better facilitate the entry of only the appropriate parameters, the agencies will provide a graphical user interface in the model for entering data specific to each vehicle. In addition, EPA will provide a template that facilitates batch processing of multiple vehicle configurations within a given family.  It is expected that this template will be submitted to EPA as part of the certification process for each certified vehicle family or subfamily.
For certification, the model will exercise the vehicle over three test cycles; one transient and two steady-state. For the transient test, we are finalizing to use the heavy-heavy-duty diesel truck (HHDDT) transient test cycle, which was developed by the California Air Resources Board and West Virginia University to evaluate heavy-duty vehicles. The transient mode simulates urban, start-stop driving, featuring 1.8 stops per mile over the 2.9 mile duration.  The two steady state test points are reflective of the tendency for some of these vehicles to operate for extended periods at highway speeds. Based on data from the EPA's MOVES database, and common highway speed limits, we are finalizing these two points to be 55 and 65 mph.
The model will predict the total emissions results from each configuration using the unique properties entered for each vehicle. These results are then normalized to the payload and distance covered, so as to yield a gram/ton-mile result, as well as a fuel consumption (gal/1,000 ton-mile) result for each test cycle.  As with engine and vehicle testing, certification will be based on the worst-case configuration within a vehicle family
The results from all three tests are then combined using weighting factors, which reflect typical usage patterns.  The typical usage characteristics of Class 7 and 8 tractors with day cabs differ significantly from Class 8 tractors with sleeper cabs.  The trucks with day cabs tend to operate in more urban areas, have a limited travel range, and tend to return to a common depot at the end of each shift.  Class 8 sleeper cabs, however, are typically used for long distance trips which consist of mostly highway driving in an effort to cover the highest mileage in the shortest time.  For these reasons, we proposed that the cycles be weighted differently for these two groups of vehicles.  For Class 7 and 8 trucks with day cabs, we proposed weights of 64%, 17%, and 19% (65 mph, 55 mph, and transient, resp.).  For Class 8 with sleeper cabs, the high speed cruise tendency results in final weights of 86%, 9%, and 5% (65 mph, 55 mph, and transient, respectively).  These final, weighted emission results are compared to the emission standard to assess compliance.
Durability Testing
As with engine certification, a manufacturer must provide evidence of compliance through the regulatory useful life of the vehicle. Factors influencing vehicle-level GHG performance over the life of the vehicle fall into two basic categories: vehicle attributes and maintenance items. Each category merits different treatment from the perspective of assessing useful life compliance, as each has varying degrees of manufacturer versus owner/operator responsibility.
The category of vehicle attributes generally refers to aerodynamic features, such as fairings, side-skirts, air dams, air foils, etc, which are installed by the manufacturer to reduce aerodynamic drag on the vehicle. These features have a significant impact on GHG emissions and their emission reduction properties are assessed early in the useful life (at the time of certification).  These features are expected to last the full life of the vehicle without becoming detached, cracked/broken, misaligned, or otherwise not in the original state.  In the absence of the aforementioned failure modes, the performance of these features is not expected to degrade over time and the benefit to reducing GHG emissions is expected to last for the life of the vehicle with no special maintenance requirements. To assess useful life compliance, we recommend a design-based approach which would ensure that the manufacturer has robustly designed these features so they can reasonably be expected to last the useful life of the vehicle.
The category of maintenance items refers to items that are replaced, renewed, cleaned, inspected, or otherwise addressed in the preventative maintenance schedule specified by the vehicle manufacturer. Items that have a direct influence on GHG emissions are primarily lubricants.  Synthetic engine oil may be used by vehicle manufacturers to reduce the GHG emissions of their vehicles. Manufacturers may specify that these fluids be changed throughout the useful life of the vehicle.  If this is the case, the manufacturer should have a reasonable basis that the owner/operator will use fluids having the same properties. This may be accomplished by requiring (in service documentation, labeling, etc) that only these fluids can be used as replacements.
If the vehicle remains in its original certified condition throughout its useful life, it is not believed that GHG emissions would increase as a result of service accumulation.  This is based on the assumption that as components wear, the rolling resistance due to friction is likely to stay the same or decrease. With all other components remaining equal (tires, aerodynamics, etc), the overall drag force would stay the same or decrease, thus not significantly changing GHG emissions at the end of useful life.  It is important to remember however, that this vehicle assessment does not take into account any engine-related wear affects, which may in fact increase GHG emissions over time.
For the reasons explained above, we believe that for the first phase of this program, it is most important to ensure that the vehicle remain in its certified configuration throughout the useful life.  This can most effectively be accomplished through engineering analysis and specific maintenance instructions provided by the vehicle manufacturer. The vehicle manufacturer would be primarily responsible for providing engineering analysis demonstrating that vehicle attributes will last for the full useful life of the vehicle. We anticipate this demonstration will show that components are constructed of sufficiently robust materials and design practices so as not to become dysfunctional under normal operating conditions.  For instance, we expect aerodynamic fairings to be constructed of materials similar to that of the main body of the vehicle (fiberglass, steel, aluminum, etc) and have sufficient support and attachment mechanisms so as not to become detached or broken under normal, on-highway driving.
EPA's Air Conditioning Leakage Standards
Heavy-duty vehicle air conditioning systems contribute to GHG emissions in two ways. First, operation of the air conditioning unit places an accessory load on the engine, which increases fuel consumption. Second, most modern refrigerants are HFC-based, which have significant global warming potential (GWP=1430). For heavy-duty vehicles, the load added by the air conditioning system is comparatively small compared to other power requirements of the vehicle. Therefore, we are not targeting any GHG reduction due to decreased air conditioning usage or higher efficiency A/C units for this final rule. However, refrigerant leakage, even in very small quantities, can have significant adverse effects on GHG emissions.
Refrigerant leakage is a concern for heavy-duty vehicles, similar to light-duty vehicles.  To address this, EPA is finalizing a design-based standard for reducing refrigerant leakage from heavy-duty vehicles.  This standard is based off using the best practices for material selection and interface sealing, as outlined in SAE publication J2727.  Based on design criteria in this publication, a leakage "score" can be assessed and an estimated annual leak rate can be made for the A/C system based on the refrigerant capacity.
At the time of certification, manufacturers will be required to outline the design of their system, including the specification of materials and construction methods.  They will also need to supply the leakage score developed using SAE J2727 and the refrigerant volume of their system to determine the leakage rate per year.  If the certifying manufacturer does not complete installation of the air conditioning unit, detailed instructions must be provided to the final installer which ensures that the A/C system is assembled to meet the low-leakage standards.  These instructions will also need to be provided at the time of certification, and manufacturers must retain all records relating to auditing of the final assembler.
In-Use Standards
As previously addressed, the drive-cycle dependence of CO2 emissions makes NTE-based in-use testing impractical.  In addition, we believe the reporting of CO2 data from the criteria pollutant in-use testing program will be helpful in future rulemaking efforts.  For these reasons, we are not finalizing an NTE-based in-use testing program for Class 7 and 8 combination tractors for this rule..
In the absence of NTE-based in-use testing, provisions are necessary for verifying that production vehicles are in the certified configuration, and remain so throughout the useful life.  Perhaps the easiest method for doing this is to verify the presence of installed emission-related components.  This would basically consist of a vehicle audit against what is claimed in the certification application. This includes verifying the presence of aerodynamic components, such as fairings, side-skirts, and gap-reducers. In addition, the presence of idle-reduction and speed limiting devices would be verified.  The presence of LRR tires could be verified at the point of initial sale; however verification at other points throughout the useful life would be non-enforceable for the reasons mentioned previously.
The category of wear items primarily relates to tires.  It is expected that vehicle manufacturers will equip their trucks with LRR tires, as they may provide a substantial reduction in GHG emissions.  The tire replacement intervals for this class of vehicle is normally in the range of 50,000 to 100,000 miles, which means the owner/operator will be replacing the tires at several points within the useful life of the vehicle.  We believe that as LRR tires become more common on new equipment, the aftermarket prices of these tires will also decrease. Along with decreasing tire prices, the fuel savings realized through use of LRR tires will ideally provide enough incentive for owner/operators to continue purchasing these tires.  The inventory modeling in this final action reflects the continued use of LRR tires through the life of the vehicle.
 Enforcement Provisions
As identified above, a significant amount of vehicle-level GHG reduction is anticipated to come from the use of components specifically designed to reduce GHG emissions.  Examples of such components include LRR tires, aerodynamic fairings, idle reduction systems, and vehicle speed limiters.  At the time of certification, vehicle manufacturers will specify which components will be on their vehicle when introduced into commerce. Based on this list of installed components, GHG emissions performance of the vehicle will be assessed using GEM, and compliance with the family (or subfamily) emissions limit will need to be shown. .  As described in the in-use testing section, it is important to have the ability to determine if the vehicle is in the certified configuration both at the time of sale, as well as at any point within the useful life.