49 CFR § 531.4 - Definitions.

---
identifier: "/us/cfr/t49/s531.4"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 531.4 - Definitions."
title_number: 49
title_name: "Transportation"
section_number: "531.4"
section_name: "Definitions."
chapter_name: "NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
part_number: "531"
part_name: "PASSENGER AUTOMOBILE AVERAGE FUEL ECONOMY STANDARDS"
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. 32902, delegation of authority at 49 CFR 1.95."
regulatory_source: "87 FR 26070, May 2, 2022, unless otherwise noted."
cfr_part: "531"
---


# 531.4 Definitions.

(a) *Statutory terms.* (1) The terms *average fuel economy, manufacture, manufacturer,* and *model year* are used as defined in 49 U.S.C. 32901.

(2) The terms *automobile* and *passenger automobile* are used as defined in 49 U.S.C. 32901 and in accordance with the determination in part 523 of this chapter.

(b) *Other terms.* As used in this part, unless otherwise required by the context—

(1) The term *domestically manufactured passenger automobile* means the vehicle is deemed to be manufactured domestically under 49 U.S.C. 32904(b)(3) and 40 CFR 600.511-08.

(2) [Reserved]

[89 FR 52945, June 24, 2024]