§ 86.1801-12 Applicability.
(a) Applicability. The provisions of this subpart apply to certain types of new vehicles as described in this paragraph (a). Where the provisions apply for a type of vehicle, they apply for vehicles powered by any fuel, unless otherwise specified. In cases where a provision applies only to a certain vehicle group based on its model year, vehicle class, motor fuel, engine type, or other distinguishing characteristics, the limited applicability is cited in the appropriate section. Testing references in this subpart generally apply to Tier 2 and older vehicles, while testing references to 40 CFR part 1066 generally apply to Tier 3 and newer vehicles; see § 86.101 for detailed provisions related to this transition. The provisions of this subpart apply to certain vehicles as follows:
(1) The provisions of this subpart apply for light-duty vehicles and light-duty trucks.
(2) The provisions of this subpart apply for medium-duty passenger vehicles. The provisions of this subpart also apply for medium-duty vehicles at or below 14,000 pounds GVWR, except as follows:
(i) The provisions of this subpart are optional for diesel-cycle vehicles through model year 2017; however, if you are using the provisions of § 86.1811-17(b)(9) or § 86.1816-18(b)(8) to transition to the Tier 3 exhaust emission standards, the provisions of this subpart are optional for those diesel-cycle vehicles until the start of the Tier 3 phase-in for those vehicles.
(ii) The exhaust emission standards of this part are optional for vehicles above 22,000 pounds GCWR and for all incomplete medium-duty vehicles. Certain requirements in this subpart apply for such vehicles even if they are not certified to the exhaust emission standards of this subpart as follows:
(A) Such vehicles remain subject to the evaporative and refueling emission standards of this subpart.
(B) [Reserved]
(C) Such vehicles may remain subject to onboard diagnostic requirements a specified in 40 CFR 1036.110.
(iii) The provisions of this subpart are optional for diesel-fueled Class 3 heavy-duty vehicles in a given model year if those vehicles are equipped with engines certified to the appropriate standards in § 86.007-11 or 40 CFR 1036.104 for which less than half of the engine family's sales for the model year in the United States are for complete Class 3 heavy-duty vehicles. This includes engines sold to all vehicle manufacturers. If you are the original manufacturer of the engine and the vehicle, base this showing on your sales information. If you manufacture the vehicle but are not the original manufacturer of the engine, you must use your best estimate of the original manufacturer's sales information.
(3) The provisions of this subpart do not apply to heavy-duty vehicles above 14,000 pounds GVWR (see § 86.016-1 and 40 CFR parts 1036 and 1037), except as follows:
(i) Heavy-duty vehicles above 14,000 pounds GVWR and at or below 19,500 pounds GVWR may be optionally certified to the exhaust emission standards in this subpart if they are properly included in a test group with similar vehicles at or below 14,000 pounds GVWR. Emission standards apply to these vehicles as if they were Class 3 medium-duty vehicles.
(ii) [Reserved]
(iii) Evaporative and refueling emission standards apply for heavy-duty vehicles above 14,000 pounds GVWR as specified in 40 CFR 1037.103.
(4) If you optionally certify vehicles to standards under this subpart, those vehicles are subject to all the regulatory requirements as if the standards were mandatory.
(b) Relationship to 40 CFR parts 1036 and 1037. If any heavy-duty vehicle is not subject to standards and certification requirements under this subpart, the vehicle and its installed engine are instead subject to standards and certification requirements under 40 CFR parts 1036 and 1037, as applicable. If you optionally certify engines or vehicles to standards under 40 CFR part 1036 or 40 CFR part 1037, respectively, those engines or vehicles are subject to all the regulatory requirements in 40 CFR parts 1036 and 1037 as if they were mandatory.
(c) Clean alternative fuel conversions. The provisions of this subpart also apply to clean alternative fuel conversions as defined in 40 CFR 85.502 of all vehicles described in paragraph (a) of this section.
(d) Small-volume manufacturers. Special certification procedures are available for small-volume manufacturers as described in § 86.1838.
(e) You. The term “you” in this subpart refers to manufacturers subject to the emission standards and other requirements of this subpart.
(f) Vehicle. The term “vehicle”, when used generically, does not exclude any type of vehicle for which the regulations apply (such as light-duty trucks).
(g) Complete and incomplete vehicles. Several provisions in this subpart, including the applicability provisions described in this section, are different for complete and incomplete vehicles. We differentiate these vehicle types as described in 40 CFR 1037.801.
(h) Applicability of provisions of this subpart to light-duty vehicles, light-duty trucks, medium-duty passenger vehicles, and heavy-duty vehicles. Numerous sections in this subpart provide requirements or procedures applicable to a “vehicle” or “vehicles.” Unless otherwise specified or otherwise determined by the Administrator, the term “vehicle” or “vehicles” in those provisions apply equally to light-duty vehicles (LDVs), light-duty trucks (LDTs), medium-duty passenger vehicles (MDPVs), and heavy-duty vehicles (HDVs), as those terms are defined in § 86.1803-01. Note that this subpart also identifies heavy-duty vehicles at or below 14,000 pounds GVWR that are not medium-duty passenger vehicles as medium-duty vehicles.
(i) Types of pollutants. Criteria pollutant standards apply for NOX, NMOG, HC, formaldehyde, PM, and CO, including exhaust, evaporative, and refueling emission standards. 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.
[89 FR 28157, Apr. 18, 2024, as amended at 91 FR 7760, Feb. 18, 2026]