49 CFR § 538.4 - Definitions.
---
identifier: "/us/cfr/t49/s538.4"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 538.4 - Definitions."
title_number: 49
title_name: "Transportation"
section_number: "538.4"
section_name: "Definitions."
chapter_name: "NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
part_number: "538"
part_name: "MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 32901, 32905, and 32906; delegation of authority at 49 CFR 1.95."
regulatory_source: "61 FR 14511, Apr. 2, 1996, unless otherwise noted."
cfr_part: "538"
---
# 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.