Section 538.4 - Definitions(a)Statutory terms.(1) The terms alternative fuel, alternative fueled automobile, and dual fueled automobile, are used as defined in 49 U.S.C. 32901(a) .(2) The terms automobile and passenger automobile, are used as defined in 49 U.S.C. 32901(a) , and in accordance with the determinations in part 523 of this chapter.(3) The term manufacturer is used as defined in 49 U.S.C. 32901(a)(13) , and in accordance with part 529 of this chapter.(4) The term model year is used as defined in 49 U.S.C. 32901(a)(15) .(b)(1) Other terms. The terms average fuel economy, fuel economy, and model type are used as defined in subpart A of 40 CFR part 600.(2) The term EPA means the U.S. Environmental Protection Agency.