40 C.F.R. § 85.502
The definitions in this section apply to this subpart. All terms that are not defined in this subpart have the meaning given in 40 CFR part 86 . All terms that are not defined in this subpart or in 40 CFR part 86 have the meaning given in the Clean Air Act. The definitions follow:
Clean alternative fuel conversion (or "fuel conversion" or "conversion system") means any alteration of a motor vehicle/engine, its fueling system, or the integration of these systems, that allows the vehicle/engine to operate on a fuel or power source different from the fuel or power source for which the vehicle/engine was originally certified; and that is designed, constructed, and applied consistent with good engineering judgment and in accordance with all applicable regulations. A clean alternative fuel conversion also means the components, design, and instructions to perform this alteration.
Clean alternative fuel conversion manufacturer (or "conversion manufacturer" or "converter") means any person that manufactures, assembles, sells, imports, or installs a motor vehicle/engine fuel conversion for the purpose of use of a clean alternative fuel.
Conversion model year means the clean alternative fuel conversion manufacturer's annual production period which includes January 1 of such calendar year. A specific model year may not include January 1 from the previous year or the following year. This is based on the expectation that production periods generally run on consistent schedules from year to year. Conversion model years may not circumvent or skip an annual production period. The term conversion model year means the calendar year if the converter does not have a different annual production period.
Date of conversion means the date on which the clean alternative fuel conversion system is fully installed and operable.
Dedicated vehicle/engine means any vehicle/engine engineered and designed to be operated using a single fuel.
Dual-fuel vehicle/engine means any vehicle/engine engineered and designed to be operated on two or more different fuels, but not on a mixture of the fuels.
Heavy-duty engines describes all engines intended for use in heavy-duty vehicles, covered under the applicability of 40 CFR part 86, subpart A.
Light-duty and heavy-duty chassis certified vehicles describes all light-duty vehicles, light-duty trucks, medium duty passenger vehicles, and heavy-duty complete and incomplete vehicles covered under the applicability of 40 CFR part 86, subpart S.
Mixed-fuel vehicle/engine means any vehicle/engine engineered and designed to be operated on the original fuel(s), alternative fuel(s), or a mixture of two or more fuels that are combusted together. Mixed-fuel vehicles/engines include flexible-fuel vehicles/engines as defined in 40 CFR part 86 subpart S.
Original equipment manufacturer (OEM) means the original manufacturer of the new vehicle/engine or relating to the vehicle/engine in its original certified configuration.
Original model year means the model year in which a vehicle/engine was originally certified by the original equipment manufacturer, as noted on the certificate and on the emission control information label.
We (us, our) means the Administrator of the Environmental Protection Agency or any authorized representative.
40 C.F.R. §85.502