Subpart B - Emission Standards and Related Requirements

§1037.101 Overview of emission standards for heavy-duty vehicles.

(a) You must show that vehicles meet the following emission standards:

(1) Exhaust emissions of criteria pollutants. Criteria pollutant standards for NO _X, HC, PM, and CO apply as described in §1037.102. These pollutants are sometimes described collectively as “criteria pollutants” because they are either criteria pollutants under the Clean Air Act or precursors to the criteria pollutants ozone and PM.

(2) [Reserved]

(3) Fuel evaporative and refueling emissions. Requirements related to fuel evaporative and refueling emissions are described in §1037.103.

(b) The regulated heavy-duty vehicles are addressed in different groups as follows:

(1) For criteria pollutants, vehicles are regulated based on gross vehicle weight rating (GVWR), whether they are considered “spark-ignition” or “compression-ignition,” and whether they are first sold as complete or incomplete vehicles.

(2) [Reserved]

(3) For evaporative and refueling emissions, vehicles are regulated based on the type of fuel they use. Vehicles fueled with volatile liquid fuels or gaseous fuels are subject to evaporative and refueling emission standards.

[88 FR 4636, Jan. 24, 2023; 89 FR 29765, Apr. 22, 2024; 91 FR 7786, Feb. 18, 2026]

§1037.102 Criteria pollutant exhaust emission standards—NO , HC, PM, and CO.

(a) Engines installed in heavy-duty vehicles are subject to criteria pollutant standards for NO _X, HC, PM, and CO under 40 CFR part 86 through model year 2026 and 40 CFR part 1036 for model years 2027 and later.

(b) Heavy-duty vehicles with no installed propulsion engine, such as battery electric vehicles, are subject to criteria pollutant standards under this part. The emission standards that apply are the same as the standards that apply for compression-ignition engines under 40 CFR 86.007-11 or 1036.104 for a given model year.

(1) You may state in the application for certification that vehicles with no installed propulsion engine comply with all the requirements of this part related to criteria emission standards instead of submitting test data. Tailpipe emissions of criteria pollutants from vehicles with no installed propulsion engine are deemed to be zero.

(2) Vehicles with no installed propulsion engines may not generate NO _X credits.

(c) Starting in model year 2024, auxiliary power units installed on new tractors, including tractors that are glider vehicles or tractors with no installed propulsion engine, must be certified to the PM emission standard specified in 40 CFR 1039.699. For model years 2021 through 2023, the APU engine must be certified under 40 CFR part 1039 with a deteriorated emission level for PM at or below 0.15 g/kW-hr. Selling, offering for sale, or introducing or delivering into commerce in the United States or importing into the United States a new tractor subject to this standard is a violation of 40 CFR 1068.101(a)(1) unless the auxiliary power unit has a valid certificate of conformity and the required label showing that it meets the PM standard specified in 40 CFR 1039.699 as described in this paragraph (c).

[88 FR 4636, Jan. 24, 2023; 89 FR 29766, Apr. 22, 2024; 91 FR 7786, Feb. 18, 2026]

§1037.103 Evaporative and refueling emission standards.

(a) Applicability. Evaporative and refueling emission standards apply to heavy-duty vehicles as follows:

(1) Complete and incomplete heavy-duty vehicles at or below 14,000 pounds GVWR must meet evaporative and refueling emission standards as specified in 40 CFR part 86, subpart S, instead of the requirements specified in this section.

(2) Heavy-duty vehicles above 14,000 pounds GVWR that run on volatile liquid fuel (such as gasoline or ethanol) or gaseous fuel (such as natural gas or LPG) must meet evaporative and refueling emission standards as specified in this section.

(b) Emission standards. The evaporative and refueling emission standards and measurement procedures specified in 40 CFR 86.1813 apply for vehicles above 14,000 pounds GVWR, except as described in this section. The evaporative emission standards phase in over model years 2018 through 2022, with provisions allowing for voluntary compliance with the standards as early as model year 2015. Count vehicles subject to standards under this section the same as heavy-duty vehicles at or below 14,000 pounds GVWR to comply with the phase-in requirements specified in 40 CFR 86.1813. These vehicles may generate and use emission credits as described in 40 CFR part 86, subpart S, but only for vehicles that are tested for certification instead of relying on the provisions of paragraph (c) of this section. The following provisions apply instead of what is specified in 40 CFR 86.1813:

(1) The refueling standards in 40 CFR 86.1813-17(b) and the related provisions in 40 CFR part 86, subpart S, apply to complete vehicles starting in model year 2022. Those standards and related provisions apply for incomplete vehicles starting in model year 2027, or as described in the alternate phase-in schedule described in 40 CFR 86.1813-17(b). If you do not certify all your incomplete heavy-duty vehicles above 14,000 pounds GVWR to the refueling standards in model year 2027, you must use the alternate phase-in schedule described in 40 CFR 86.1813-17(b).

(2) The leak standard in 40 CFR 86.1813-17(a)(4) does not apply.

(3) The FEL cap relative to the diurnal plus hot soak standard for low-altitude testing is 1.9 grams per test.

(4) The diurnal plus hot soak standard for high-altitude testing is 2.3 grams per test.

(5) Testing does not require measurement of exhaust emissions. Disregard references in subpart B of this part to procedures, equipment specifications, and recordkeeping related to measuring exhaust emissions. All references to the exhaust test under 40 CFR part 86, subpart B, are considered the “dynamometer run” as part of the evaporative testing sequence under this subpart.

(c) Compliance demonstration. You may provide a statement in the application for certification that vehicles above 14,000 pounds GVWR comply with evaporative and refueling emission standards in this section instead of submitting test data if you include an engineering analysis describing how vehicles include design parameters, equipment, operating controls, or other elements of design that adequately demonstrate that vehicles comply with the standards throughout the useful life. We would expect emission control components and systems to exhibit a comparable degree of control relative to vehicles that comply based on testing. For example, vehicles that comply under this paragraph (c) should rely on comparable material specifications to limit fuel permeation, and components should be sized and calibrated to correspond with the appropriate fuel capacities, fuel flow rates, purge strategies, and other vehicle operating characteristics. You may alternatively show that design parameters are comparable to those for vehicles at or below 14,000 pounds GVWR certified under 40 CFR part 86, subpart S.

(d) CNG refueling requirement. Compressed natural gas vehicles must meet the requirements for fueling connection devices as specified in 40 CFR 86.1813-17(f)(1). Vehicles meeting these requirements are deemed to comply with evaporative and refueling emission standards.

(e) LNG refueling requirement. Fuel tanks for liquefied natural gas vehicles must meet the hold-time requirements in Section 4.2 of SAE J2343 (incorporated by reference, see §1037.810), as modified by this paragraph (e). All pressures noted are gauge pressure. Vehicles with tanks meeting the requirements in this paragraph (e) are deemed to comply with evaporative and refueling emission standards. The provisions of this paragraph (e) are optional for vehicles produced before January 1, 2020. The hold-time requirements of SAE J2343 apply, with the following clarifications and additions:

(1) Hold time must be at least 120 hours. Use the following procedure to determine hold time for an LNG fuel tank that will be installed on a heavy-duty vehicle:

(i) Prepare the stored (offboard) fuel and the vehicle such that tank pressure after the refuelingevent stabilizes below 690 kPa.

(ii) Fill the tank to the point of automatic shutoff using a conventional refueling system. This is intended to achieve a net full condition.

(iii) The hold time starts when tank pressure increases to 690 kPa, and ends when the tank first vents for pressure relief. Use good engineering judgment to document the point at which the pressure-relief valve opens.

(iv) Keep the tank at rest away from direct sun with ambient temperatures between (10 and 30)°C throughout the measurement procedure.

(2) Following a complete refueling event as described in paragraph (e)(1) of this section and a short drive, installed tanks may not increase in pressure by more than 9 kPa per hour over a minimum 12 hour interval when parked away from direct sun with ambient temperatures at or below 30°C. Calculate the allowable pressure gain by multiplying the park time in hours by 9 and rounding to the nearest whole number. Do not include the first hour after engine shutdown, and start the test only when tank pressure is between 345 and 900 kPa.

(3) The standards described in this paragraph (e) apply over the vehicle's useful life as specified in paragraph (f) of this section. The warranty requirements of §1037.120 also apply for these standards.

(4) You may specify any amount of inspection and maintenance, consistent with good engineering judgment, to ensure that tanks meet the standards in this paragraph (e) during and after the useful life.

(f) Useful life. The evaporative and refueling emission standards of this section apply for the full useful life, expressed in service miles or calendar years, whichever comes first. The useful life values for the standards of this section are the same as the values described for evaporative emission standards in 40 CFR 86.1805.

(g) Auxiliary engines and separate fuel systems. The provisions of this paragraph (g) apply for vehicles with auxiliary engines. This includes any engines installed in the final vehicle configuration that contribute no motive power through the vehicle's transmission.

(1) Auxiliary engines and associated fuel-system components must be installed when testing fully assembled vehicles. If the auxiliary engine draws fuel from a separate fuel tank, you must fill the extra fuel tank before the start of diurnal testing as described for the vehicle's main fuel tank. Use good engineering judgment to ensure that any nonmetal portions of the fuel system related to the auxiliary engine have reached stabilized levels of permeation emissions. The auxiliary engine must not operate during the running loss test or any other portion of testing under this section.

(2) For testing with partially assembled vehicles, you may omit installation of auxiliary engines and associated fuel-system components as long as those components installed in the final configuration are certified to meet the applicable emission standards for Small SI equipment described in 40 CFR 1054.112 or for Large SI engines in 40 CFR 1048.105. For any fuel-system components that you do not install, your installation instructions must describe this certification requirement.

[86 FR 34459, Jun. 29, 2021; 88 FR 4636, Jan. 24, 2023; 89 FR 29766, Apr. 22, 2024]

§1037.115 Other requirements.

Vehicles required to meet the emission standards of this part must meet the following additional requirements, except as noted elsewhere in this part:

(a) Adjustable parameters. Vehicles that have adjustable parameters must meet all the requirements of this part for any adjustment in the practically adjustable range. We may require that you set adjustable parameters to any specification within the practically adjustable range during any testing. See 40 CFR 1068.50 for general provisions related to adjustable parameters. You must ensure safe vehicle operation throughout the practically adjustable range of each adjustable parameter, including consideration of production tolerances. Note that adjustable roof fairings are deemed not to be adjustable parameters.

(b) Prohibited controls. You may not design your vehicles with emission control devices, systems, or elements of design that cause or contribute to an unreasonable risk to public health, welfare, or safety while operating. For example, this would apply if the vehicle emits a noxious or toxic substance it would otherwise not emit that contributes to such an unreasonable risk.

(c) [Reserved]

(d) Defeat devices. 40 CFR 1068.101 prohibits the use of defeat devices.

[86 FR 34459, Jun. 29, 2021; 88 FR 4637, Jan. 24, 2023; 89 FR 29771, Apr. 22, 2024; 91 FR 7786, Feb. 18, 2026]

§1037.120 Emission-related warranty requirements.

(a) General requirements. You must warrant to the ultimate purchaser and each subsequent purchaser that each new vehicle, including all parts of its emission control system, meets two conditions:

(1) It is designed, built, and equipped so it conforms at the time of sale to the ultimate purchaser with the requirements of this part.

(2) It is free from defects in materials and workmanship that cause the vehicle to fail to conform to the requirements of this part during the applicable warranty period.

(b) Warranty period. (1) Your emission-related warranty must be valid for at least:

(i) 5 years or 50,000 miles for Light HDV.

(ii) 5 years or 100,000 miles for heavy-duty vehicles above 19,500 pounds GVWR.

(2) You may offer an emission-related warranty more generous than we require. The emission-related warranty for the vehicle may not be shorter than any basic mechanical warranty you provide to that owner without charge for the vehicle. Similarly, the emission-related warranty for any component may not be shorter than any warranty you provide to that owner without charge for that component. This means that your warranty for a given vehicle may not treat emission-related and nonemission-related defects differently for any component. The warranty period begins when the vehicle is placed into service.

(c) Components covered. The emission-related warranty covers fuel cell stacks, RESS, and other components used with battery electric vehicles and fuel cell electric vehicles. The emission-related warranty covers all components whose failure would increase a vehicle's evaporative and refueling emissions (for vehicles subject to evaporative and refueling emission standards). The emission-related warranty covers components that are part of your certified configuration even if another company produces the component.

(d) Limited applicability. You may deny warranty claims under this section if the operator caused the problem through improper maintenance or use, as described in 40 CFR 1068.115.

(e) Owners manual. Describe in the owners manual the emission-related warranty provisions from this section that apply to the vehicle.

[86 FR 34460, Jun. 29, 2021; 88 FR 4637, Jan. 24, 2023; 89 FR 29772, Apr. 22, 2024; 91 FR 7786, Feb. 18, 2026]

§1037.125 Maintenance instructions and allowable maintenance.

Give the ultimate purchaser of each new vehicle written instructions for properly maintaining and using the vehicle, including the emission control system. The maintenance instructions also apply to service accumulation on any of your emission-data vehicles. See paragraph (i) of this section for requirements related to tire replacement.

[88 FR 4637, Jan. 24, 2023; 91 FR 7787, Feb. 18, 2026]

§1037.130 Assembly instructions for secondary vehicle manufacturers.

(a) If you sell a certified incomplete vehicle to a secondary vehicle manufacturer, give the secondary vehicle manufacturer instructions for completing vehicle assembly consistent with the requirements of this part. Include all information necessary to ensure that the final vehicle assembly (including the engine) will be in its certified configuration.

(b) Make sure these instructions have the following information:

(1) Include the heading: “Emission-related installation instructions”.

(2) State: “Failing to follow these instructions when completing assembly of a heavy-duty motor vehicle violates federal law, subject to fines or other penalties as described in the Clean Air Act.”

(3) Describe the necessary steps for installing emission-related diagnostic systems.

(4) Describe how your certification is limited for any type of application, as illustrated in the following examples:

(i) If the incomplete vehicle is at or below 8,500 pounds GVWR, state that the vehicle's certification is valid under this part 1037 only if the final configuration has a vehicle curb weight above 6,000 pounds or basic vehicle frontal area above 45 square feet.

(ii) If your engine will be installed in a vehicle that you certify to meet diurnal emission standards using an evaporative canister, but you do not install the fuel tank, identify the maximum permissible fuel tank capacity.

(5) Describe any other instructions to make sure the vehicle will operate according to design specifications in your application for certification.

(c) Provide instructions in writing or in an equivalent format. You may include this information with the incomplete vehicle document required by DOT. If you do not provide the instructions in writing, explain in your application for certification how you will ensure that each installer is informed of the installation requirements.

[88 FR 4637, Jan. 24, 2023; 89 FR 29772, Apr. 22, 2024]

§1037.135 Labeling.

(a) Assign each vehicle a unique identification number and permanently affix, engrave, or stamp it on the vehicle in a legible way. The vehicle identification number (VIN) serves this purpose.

(b) At the time of manufacture, affix a permanent and legible label identifying each vehicle. The label must meet the requirements of 40 CFR 1068.45.

(c) The label must -

(1) Include the heading “VEHICLE EMISSION CONTROL INFORMATION”.

(2) Include your full corporate name and trademark. You may identify another company and use its trademark instead of yours if you comply with the branding provisions of 40 CFR 1068.45.

(3) Include EPA's standardized designation for the vehicle family.

(4) [Reserved]

(5) State the date of manufacture [DAY (optional), MONTH, and YEAR]. You may omit this from the label if you stamp, engrave, or otherwise permanently identify it elsewhere on the vehicle, in which case you must also describe in your application for certification where you will identify the date on the vehicle.

(6)-(7) [Reserved]

(8) State: “THIS VEHICLE COMPLIES WITH U.S. EPA REGULATIONS FOR [MODEL YEAR] HEAVY-DUTY VEHICLES.”

(9) If you rely on another company to design and install fuel tanks in incomplete vehicles that use an evaporative canister for controlling diurnal emissions, include the following statement: “THIS VEHICLE IS DESIGNED TO COMPLY WITH EVAPORATIVE EMISSION STANDARDS WITH UP TO x GALLONS OF FUEL TANK CAPACITY.” Complete this statement by identifying the maximum specified fuel tank capacity associated with your certification.

(d) You may add information to the emission control information label as follows:

(1) You may identify other emission standards that the vehicle meets or does not meet (such as European standards).

(2) You may add other information to ensure that the vehicle will be properly maintained and used.

(3) You may add appropriate features to prevent counterfeit labels. For example, you may include the vehicle's unique identification number on the label.

(e) You may ask us to approve modified labeling requirements in this part 1037 if you show that it is necessary or appropriate. We will approve your request if your alternate label is consistent with the requirements of this part.

[86 FR 34460, Jun. 29, 2021; 88 FR 4638, Jan. 24, 2023; 89 FR 29772, Apr. 22, 2024; 91 FR 7787, Feb. 18, 2026]

§1037.140 Classifying vehicles and determining vehicle parameters.

(a) Where applicable, a vehicle's roof height and a trailer's length are determined from nominal design specifications, as provided in this section. Specify design values for roof height and trailer length to the nearest inch.

(b) Base roof height on fully inflated tires having a static loaded radius equal to the arithmetic mean of the largest and smallest static loaded radius of tires you offer or a standard tire we approve.

(c) Base a standard trailer's length on the outer dimensions of the load-carrying structure. Do not include aerodynamic devices or HVAC units.

(d) The nominal design specifications must be within the range of the actual values from production vehicles considering normal production variability. In the case of roof height, use the mean tire radius specified in paragraph (b) of this section. If after production begins it is determined that your nominal design specifications do not represent production vehicles, we may require you to amend your application for certification under §1037.225.

(e) If your vehicle is equipped with an adjustable roof fairing, measure the roof height with the fairing in its lowest setting.

(f) For any provisions in this part that depend on the number of axles on a vehicle, include lift axles or any other installed axles that can be used to carry the vehicle's weight while in motion.

(g) The provisions of this part relating to NHTSA's fuel efficiency program under 49 CFR part 535 apply to specific vehicle service classes as follows:

(1) Tractors are divided based on GVWR into Class 7 tractors and Class 8 tractors. Where provisions of this part apply to both tractors and vocational vehicles, Class 7 tractors are considered “Medium HDV” and Class 8 tractors are considered “Heavy HDV”. This paragraph (g)(1) applies for hybrid and non-hybrid vehicles.

(2) Phase 1 vocational vehicles are divided based on GVWR. “Light HDV” includes Class 2b through Class 5 vehicles; “Medium HDV” includes Class 6 and Class 7 vehicles; and “Heavy HDV” includes Class 8 vehicles.

(3) Phase 2 and later vocational vehicles propelled by engines subject to the spark-ignition standards of 40 CFR part 1036 are divided as follows:

(i) Class 2b through Class 5 vehicles are considered “Light HDV”.

(ii) Class 6 through Class 8 vehicles are considered “Medium HDV”.

(4) Phase 2 and later vocational vehicles propelled by engines subject to the compression-ignition standards in 40 CFR part 1036 are divided as follows:

(i) Class 2b through Class 5 vehicles are considered “Light HDV”.

(ii) Class 6 through 8 vehicles are considered “Heavy HDV” if the installed engine's primary intended service class is Heavy HDE (see 40 CFR 1036.140), except that Class 8 hybrid vehicles are considered “Heavy HDV” regardless of the engine's primary intended service class.

(iii) All other Class 6 through Class 8 vehicles are considered “Medium HDV”.

(5) Heavy-duty vehicles with no installed propulsion engine, such as battery electric vehicles, are divided as follows:

(i) Class 2b through Class 5 vehicles are considered “Light HDV”.

(ii) Class 6 and 7 vehicles are considered “Medium HDV”.

(iii) Class 8 vehicles are considered “Heavy HDV”.

(6) In certain circumstances, you may certify vehicles to standards that apply for a different vehicle service class. If you optionally certify vehicles to different standards, those vehicles are subject to all the regulatory requirements as if the standards were mandatory.

(7) Custom chassis vehicles are subject to the following vehicle service classes instead of the other provisions in this section:

(i) School buses and motor homes are considered “Medium HDV”.

(ii) All other custom-chassis are considered “Heavy HDV”.

(h) Use good engineering judgment to identify the intended regulatory subcategory (Urban, Multi-Purpose, or Regional) for each of your vocational vehicle configurations based on the expected use of the vehicles.

[86 FR 34460, Jun. 29, 2021; 88 FR 4638, Jan. 24, 2023; 89 FR 29772, Apr. 22, 2024; 91 FR 7787, Feb. 18, 2026]

§1037.150 Interim provisions.

The provisions in this section apply instead of other provisions in this part.

(a) Incentives for early introduction. The provisions of this paragraph (a) apply with respect to vehicles produced in model years before 2014. Manufacturers may voluntarily certify in model year 2013 (or earlier model years for electric vehicles) to the fuel consumption standards of 49 CFR part 535.

(1) This paragraph (a)(1) applies for regulatory subcategories subject to the standards of 49 CFR part 535. Except as specified in paragraph (a)(3) of this section, to generate early credits under this paragraph (a)(1) for any vehicles other than electric vehicles, you must certify your entire U.S.-directed production volume within the regulatory subcategory to the standards of 49 CFR part 535. Except as specified in paragraph (a)(4) of this section, if some vehicle families within a regulatory subcategory are certified after the start of the model year, you may generate credits only for production that occurs after all families are certified. For example, if you produce three vehicle families in an averaging set and you receive your certificates for those families on January 4, 2013, March 15, 2013, and April 24, 2013, you may not generate credits for model year 2013 production in any of the families that occurs before April 24, 2013. Calculate credits relative to the standard that would apply in model year 2014 using the equations in subpart H of this part. You may bank credits equal to the surplus credits you generate under this paragraph (a) multiplied by 1.50. For example, if you have 1.0 Mg of surplus credits for model year 2013, you may bank 1.5 Mg of credits. Credit deficits for an averaging set prior to model year 2014 do not carry over to model year 2014. These credits may be used to show compliance with the standards of this part for 2014 and later model years. We recommend that you notify us of your intent to use this paragraph (a)(1) before submitting your applications.

(2) [Reserved]

(3) You may generate credits for the number of additional SmartWay designated tractors (relative to your 2012 production), provided you do not generate credits for those vehicles under paragraph (a)(1) of this section. Calculate credits for each regulatory subcategory relative to the standard that would apply in model year 2014 using the equations in subpart H of this part. Use a production volume equal to the number of designated model year 2013 SmartWay tractors minus the number of designated model year 2012 SmartWay tractors. You may bank credits equal to the surplus credits you generate under this paragraph (a)(3) multiplied by 1.50. Your 2012 and 2013 model years must be equivalent in length.

(4) This paragraph (a)(4) applies where you do not receive your final certificate in a regulatory subcategory within 30 days of submitting your final application for that subcategory. Calculate your credits for all production that occurs 30 days or more after you submit your final application for the subcategory.

(b) Phase 1 coastdown procedures. For tractors subject to Phase 1 standards, the default method for measuring drag area ( C_dA ) is the coastdown procedure specified in 40 CFR part 1066, subpart D. This includes preparing the tractor and the standard trailer with wheels meeting specifications of §1037.528(b) and submitting information related to your coastdown testing under §1037.528(h).

(c) Small manufacturers. The following provisions apply for qualifying small manufacturers:

(1) The fuel consumption standards under 49 CFR part 535 are optional for small manufacturers producing vehicles with a date of manufacture before January 1, 2022. In addition, small manufacturers producing vehicles that run on any fuel other than gasoline, E85, or diesel fuel may delay complying with every later standard under this part by one model year.

(2) Qualifying manufacturers must notify the Designated Compliance Officer each model year before introducing excluded vehicles into U.S. commerce. This notification must include a description of the manufacturer's qualification as a small business under 13 CFR 121.201.

(3) Small manufacturers may meet Phase 1 standards instead of Phase 2 standards in the first year Phase 2 standards apply to them if they voluntarily comply with the Phase 1 standards for the full preceding year. Specifically, small manufacturers may certify their model year 2022 vehicles to the Phase 1 fuel consumption standards under 49 CFR part 535 if they certify all the vehicles from their annual production volume included in emission credit calculations for the Phase 1 standards starting on or before January 1, 2021.

(4) See paragraphs (r), (t), (u), and (w) of this section for additional allowances for small manufacturers.

(d)-(f) [Reserved]

(g) Compliance date. Compliance with the standards of this part was optional prior to January 1, 2014. This means that if your 2014 model year begins before January 1, 2014, you may certify for a partial model year that begins on January 1, 2014, and ends on the day your model year would normally end.

(h) Off-road vehicle exemption. (1) Vocational vehicles with a date of manufacture before January 1, 2021, automatically qualify for an exemption under §1037.631 if the tires installed on the vehicle have a maximum speed rating at or below 55 miles per hour.

(2) In unusual circumstances, vehicle manufacturers may ask us to exempt vehicles under §1037.631 based on other criteria that are equivalent to those specified in §1037.631(a); however, we will normally not grant relief in cases where the vehicle manufacturer has credits or can otherwise comply with applicable standards. Request approval for an exemption under this paragraph (h) before you produce the subject vehicles.

(i) Limited carryover from Phase 1 to Phase 2. The provisions for carryover data in §1037.235(d) do not allow you to use aerodynamic test results from Phase 1 to support a compliance demonstration for Phase 2 certification.

(j) Limited prohibition related to early model year engines. The provisions of this paragraph (j) apply only for vehicles that have a date of manufacture before January 1, 2018. See §1037.635 for related provisions that apply in later model years. The prohibition in §1037.601 against introducing into U.S. commerce a vehicle containing an engine not certified to the standards applicable for the calendar year of installation does not apply for vehicles using model year 2014 or 2015 spark-ignition engines, or any model year 2013 or earlier engines.

(k) Verifying drag areas from in-use tractors. This paragraph (k) applies for tractors instead of §1037.401(b) through model year 2020. We may measure the drag area of your vehicles after they have been placed into service. To account for measurement variability, your vehicle is deemed to conform to the regulations of this part with respect to aerodynamic performance if we measure its drag area to be at or below the maximum drag area allowed for the bin above the bin to which you certified (for example, Bin II if you certified the vehicle to Bin III), unless we determine that you knowingly produced the vehicle to have a higher drag area than is allowed for the bin to which it was certified.

(l) [Reserved]

(m) Loose engine sales. Manufacturers may certify certain spark-ignition engines along with chassis-certified heavy-duty vehicles where they are identical to engines used in those vehicles as described in 40 CFR 86.1819-14(k)(8). Vehicles in which those engines are installed are subject to standards under 49 CFR part 535.

(n) Transition to engine-based model years. The following provisions apply for production and ABT reports during the transition to engine-based model year determinations for vehicles in 2020 and 2021:

(1) If you install model year 2020 or earlier engines in your vehicles in calendar year 2020, include all those Phase 1 vehicles in your production and ABT reports related to model year 2020 compliance, although we may require you identify these separately from vehicles produced in calendar year 2019.

(2) If you install model year 2020 engines in your vehicles in calendar year 2021, submit production and ABT reports for those Phase 1 vehicles separate from the reports you submit for Phase 2 vehicles with model year 2021 engines.

(o)-(p) [Reserved]

(q) Vehicle families for advanced and off-cycle technologies. Apply the following provisions for grouping vehicles into families if you use off-cycle technologies under §1037.610 or advanced technologies under §1037.615:

(1) For Phase 1 vehicles, create separate vehicle families for vehicles that contain advanced or off-cycle technologies; group those vehicles together in a vehicle family if they use the same advanced or off-cycle technologies.

(2) For Phase 2 vehicles, create separate vehicle subfamilies for vehicles that contain advanced or off-cycle technologies; group those vehicles together in a vehicle subfamily if they use the same advanced or off-cycle technologies.

(r) Conversion to mid-roof and high-roof configurations. Secondary vehicle manufacturers that qualify as small manufacturers may convert low- and mid-roof tractors to mid- and high-roof configurations without recertification for the purpose of building a custom sleeper tractor or converting it to run on natural gas, as follows:

(1) The original low- or mid-roof tractor must be covered by a valid certificate of conformity.

(2) The modifications may not increase the frontal area of the tractor beyond the frontal area of the equivalent mid- or high-roof tractor with the corresponding standard trailer. Note that these dimensions have a tolerance of ±2 inches. Use good engineering judgment to achieve aerodynamic performance similar to or better than the certifying manufacturer's corresponding mid- or high-roof tractor.

(3) [Reserved]

(4) We may require that you submit annual production reports as described in §1037.250.

(5) Modifications made under this paragraph (r) do not violate 40 CFR 1068.101(b)(1).

(s) Confirmatory testing for F. If we conduct coastdown testing to verify your F_alt-aero value for Phase 2 and later tractors, we will make our determination using the principles of SEA testing in §1037.305. We will not replace your F_alt-aero value if the tractor passes. If your tractor fails, we will generate a replacement value of F_alt-aero based on at least one C_dA value and corresponding effective yaw angle, _eff , from a minimum of 100 valid runs using the procedures of §1037.528(h). Note that we intend to minimize the differences between our test conditions and those of the manufacturer by testing at similar times of the year where possible and the same location where possible and when appropriate.

(t) Glider kits and glider vehicles. (1) Glider vehicles conforming to the requirements in this paragraph (t)(1) are exempt from the Phase 1 emission standards of this part 1037 prior to January 1, 2021. Engines in such vehicles (including vehicles produced after January 1, 2021) remain subject to the requirements of 40 CFR part 86 applicable for the engines' original model year, but not subject to the Phase 1 or Phase 2 standards of 40 CFR part 1036 unless they were originally manufactured in model year 2014 or later.

(i) You are eligible for the exemption in this paragraph (t)(1) if you are a small manufacturer and you sold one or more glider vehicles in 2014 under the provisions of paragraph (c) of this section. You do not qualify if you only produced glider vehicles for your own use. You must notify us of your plans to use this exemption before you introduce exempt vehicles into U.S. commerce. In your notification, you must identify your annual U.S.-directed production volume (and sales, if different) of such vehicles for calendar years 2010 through 2014. Vehicles you produce before notifying us are not exempt under this section.

(ii) In a given calendar year, you may produce up to 300 exempt vehicles under this section, or up to the highest annual production volume you identify in this paragraph (t)(1), whichever is less.

(iii) Identify the number of exempt vehicles you produced under this exemption for the preceding calendar year in your annual report under §1037.250.

(iv) Include the appropriate statement on the label required under §1037.135, as follows:

(A) For Phase 1 vehicles, “THIS VEHICLE AND ITS ENGINE ARE EXEMPT UNDER 40 CFR 1037.150(t)(1).”

(B) For Phase 2 vehicles, “THE ENGINE IN THIS VEHICLE IS EXEMPT UNDER 40 CFR 1037.150(t)(1).”

(v) If you produce your glider vehicle by installing remanufactured or previously used components in a glider kit produced by another manufacturer, you must provide the following to the glider kit manufacturer prior to obtaining the glider kit:

(A) Your name, the name of your company, and contact information.

(B) A signed statement that you are a qualifying small manufacturer and that your production will not exceed the production limits of this paragraph (t)(1). This statement is deemed to be a submission to EPA, and we may require the glider kit manufacturer to provide a copy to us at any time.

(vi) The exemption in this paragraph (t)(1) is valid for a given vehicle and engine only if you meet all the requirements and conditions of this paragraph (t)(1) that apply with respect to that vehicle and engine. Introducing such a vehicle into U.S. commerce without meeting all applicable requirements and conditions violates 40 CFR 1068.101(a)(1).

(vii) Companies that are not small manufacturers may sell uncertified incomplete vehicles without engines to small manufacturers for the purpose of producing exempt vehicles under this paragraph (t)(1), subject to the provisions of §1037.622. However, such companies must take reasonable steps to ensure that their incomplete vehicles will be used in conformance with the requirements of this part.

(2) Glider vehicles produced using engines certified to model year 2010 or later standards for all pollutants are subject to the same provisions that apply to vehicles using engines within their useful life in §1037.635.

(3) For calendar year 2017, you may produce a limited number of glider kits and/or glider vehicles subject to the requirements applicable to model year 2016 glider vehicles, instead of the requirements of §1037.635. The limit applies to your combined 2017 production of glider kits and glider vehicles and is equal to your highest annual production of glider kits and glider vehicles for any year from 2010 to 2014. Any glider kits or glider vehicles produced beyond this cap are subject to the provisions of §1037.635. Count any glider kits and glider vehicles you produce under paragraph (t)(1) of this section as part of your production with respect to this paragraph (t)(3).

(u) Transition to Phase 2 standards. The following provisions allow for enhanced generation and use of emission credits from Phase 1 vehicles for meeting the Phase 2 standards:

(1) For vocational Light HDV and vocational Medium HDV, credits you generate in model years 2018 through 2021 may be used through model year 2027, instead of being limited to a five-year credit life as specified in §1037.740(c). For Class 8 vocational vehicles with Medium HDE, we will approve your request to generate these credits in and use these credits for the Medium HDV averaging set if you show that these vehicles would qualify as Medium HDV under the Phase 2 program as described in §1037.140(g)(4).

(2) You may use the off-cycle provisions of §1037.610 to apply technologies to Phase 1 vehicles as follows:

(i) You may apply an improvement factor of 0.988 for vehicles with automatic tire inflation systems on all axles.

(ii) For vocational vehicles with automatic engine shutdown systems that conform with §1037.660, you may apply an improvement factor of 0.95.

(iii) For vocational vehicles with stop-start systems that conform with §1037.660, you may apply an improvement factor of 0.92.

(iv) For vocational vehicles with neutral-idle systems conforming with §1037.660, you may apply an improvement factor of 0.98. You may adjust this improvement factor if we approve a partial reduction under §1037.660(a)(2); for example, if your design reduces fuel consumption by half as much as shifting to neutral, you may apply an improvement factor of 0.99.

(3) Small manufacturers may generate credits for natural gas-fueled vocational vehicles as follows:

(i) Small manufacturers may certify their vehicles instead of relying on the exemption of paragraph (c) of this section. The provisions of this part apply for such vehicles, except as specified in this paragraph (u)(3).

(ii) Use GEM version 2.0.1 to determine a fuel consumption level for your vehicle, then multiply this value by the engine's Family Certification Level for CO ₂ and divide by the engine's applicable fuel consumption standard.

(4) Phase 1 vocational vehicle credits that small manufacturers generate may be used through model year 2027.

(v) [Reserved]

(w) Custom-chassis standards for small manufacturers. The following provisions apply uniquely to qualifying small manufacturers under the custom-chassis standards of §1037.105(h):

(1) You may use emission credits generated under §1037.105(d), including banked or traded credits from any averaging set. Such credits remain subject to other limitations that apply under subpart H of this part.

(2) You may produce up to 200 drayage tractors in a given model year to the standards described in §1037.105(h) for “other buses”. The limit in this paragraph (w)(2) applies with respect to vehicles produced by you and your affiliated companies. Treat these drayage tractors as being in their own averaging set.

(x) Transition to updated GEM. (1) Vehicle manufacturers may demonstrate compliance with Phase 2 greenhouse gas standards in model years 2021 through 2023 using GEM Phase 2, Version 3.0, Version 3.5.1, or Version 4.0 (all incorporated by reference, see §1037.810). Manufacturers may change to a different version of GEM for model years 2022 and 2023 for a given vehicle family after initially submitting an application for certification; such a change must be documented as an amendment under §1037.225. Manufacturers may submit an end-of-year report for model year 2021 using any of the three regulatory versions of GEM, but only for demonstrating compliance with the custom-chassis standards in §1037.105(h); such a change must be documented in the report submitted under §1037.730. Once a manufacturer certifies a vehicle family based on GEM Version 4.0, it may not revert back to using GEM Phase 2, Version 3.0 or Version 3.5.1 for that vehicle family in any model year.

(2) Vehicle manufacturers may certify for model years 2021 through 2023 based on fuel maps from engines or powertrains that were created using GEM Phase 2, Version 3.0, Version 3.5.1, or Version 4.0 (all incorporated by reference, see §1037.810). Vehicle manufacturers may alternatively certify in those years based on fuel maps from powertrains that were created using GEM Phase 2, Version 3.0, GEM HIL model 3.8, or GEM Phase 2, Version 4.0 (all incorporated by reference, see §1037.810). Vehicle manufacturers may continue to certify vehicles in later model years using fuel maps generated with earlier versions of GEM for model year 2024 and later vehicle families that qualify for using carryover provisions in §1037.235(d).

(y) [Reserved]

(z) Constraints for vocational regulatory subcategories. The following provisions apply to determinations of vocational regulatory subcategories as described in §1037.140:

(1) Select the Regional regulatory subcategory for coach buses and motor homes.

(2) You may not select the Urban regulatory subcategory for any vehicle with a manual or single-clutch automated manual transmission.

(3) Starting in model year 2024, you must select the Regional regulatory subcategory for any vehicle with a manual transmission.

(4) You may select the Multi-purpose regulatory subcategory for any vocational vehicle, except as specified in paragraph (v)(1) of this section.

(5) You may select the Urban regulatory subcategory for a hybrid vehicle equipped with regenerative braking, unless it is equipped with a manual transmission.

(aa) Warranty for components used with battery electric vehicles and fuel cell electric vehicles. The emission-related warranty requirements in §1037.120 are optional for fuel cell stacks, RESS, and other components used with battery electric vehicles and fuel cell electric vehicles before model year 2027.

[86 FR 34460, Jun. 29, 2021; 87 FR 45264, July 28, 2022; 88 FR 4638, Jan. 24, 2023; 89 FR 28211, Apr. 18, 2024; 89 FR 29772, Apr. 22, 2024; 91 FR 7787, Feb. 18, 2026]