Light-duty truck means any motor vehicle rated at 8,500 pounds GVWR or less which as a vehicle curb weight of 6,000 pounds or less and which has a basic vehicle frontal area of 45 square feet or less, which is:
(1) Designed primarily for purposes of transportation of property or is a derivation of such a vehicle, or
(2) Designed primarily for transportation of persons and has a capacity of more than 12 persons, or
(3) Available with special features enabling off-street or off-highway operation and use.
40 CFR § 86.082-2
The definitions of this section apply to this subpart and also to subparts B, D, I, and R of this part.