Section 1037.101 - Overview of emission standards(a) You must show that vehicles meet the following emission standards: (1)Exhaust emissions of criteria pollutants. Criteria pollutant standards for NOX, 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)Exhaust emissions of greenhouse gases. This part contains standards and other regulations applicable to the emission of the air pollutant defined as the aggregate group of six greenhouse gases: carbon dioxide, nitrous oxide, methane, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Emission standards apply as follows for greenhouse gas emissions:(i) CO2 emission standards apply as described in §§ 1037.105 and 1037.106 . No CH4 or N2O standards apply under this part. See 40 CFR part 1036 for CH4 or N2O standards that apply to engines used in these vehicles.(ii) Hydrofluorocarbon standards apply as described in § 1037.115(e) . These pollutants are also "greenhouse gas pollutants" but are treated separately from exhaust greenhouse gas pollutants listed in paragraph (a)(2)(i) of this section.(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) Greenhouse gas standards apply differently for vocational vehicles and tractors. Greenhouse gas standards also apply differently depending on the vehicle service class as described in § 1037.140 . In addition, standards apply differently for vehicles with spark-ignition and compression-ignition engines. References in this part to "spark-ignition" or "compression-ignition" generally relate to the application of standards under 40 CFR 1036.140 . For example, a vehicle with an engine certified to spark-ignition standards under 40 CFR part 1036 is generally subject to requirements under this part that apply for spark-ignition vehicles. However, note that emission standards for Heavy HDE are considered to be compression-ignition standards for purposes of applying vehicle emission standards under this part. Also, for spark-ignition engines voluntarily certified as compression-ignition engines under 40 CFR part 1036, you must choose at certification whether your vehicles are subject to spark-ignition standards or compression-ignition standards. Heavy-duty vehicles with no installed propulsion engine, such as battery electric vehicles, are subject to compression-ignition emission standards under §§ 1037.105 and 1037.106 for the purpose of calculating emission credits.(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 4635, Jan. 24, 2023; as amended at 89 FR 29765, Apr. 22, 2024 88 FR 4635, 3/27/2023; as amended at 89 FR 29765, 6/21/2024