Title 49 › SUBTITLE VI — MOTOR VEHICLE AND DRIVER PROGRAMS › PART C — INFORMATION, STANDARDS, AND REQUIREMENTS › CHAPTER 329 — AUTOMOBILE FUEL ECONOMY › § 32904
The EPA must work out each carmaker’s average fuel economy. For most cars it uses a formula that totals the cars made and divides by a sum of each model’s share divided by that model’s tested fuel economy. Electric cars are counted using “equivalent” gasoline-mile numbers set by the Energy Secretary, who must review those values every year based on vehicle efficiency, how electricity is generated and delivered, national energy needs and scarcity, and how people use electric cars. The EPA must use fuel-economy test methods like those used in model year 1975 (55% city, 45% highway) or methods that give similar results, round results to the nearest 0.1 mile per gallon, decide how much of other fuels equal one gallon of gasoline, and, when possible, run fuel tests at the same time as emissions tests. Any new or changed testing procedure (other than a clerical change) must be announced at least 12 months before the model year it applies to. The EPA must make separate average calculations for cars made “domestically” and those made elsewhere. A car counts as domestic if at least 75% of its cost came from work done in the United States or Canada (special rules apply if assembly was finished in Canada and the car is imported more than 30 days after the model year ends). A rule that can include Mexico in the 75% test applies to some manufacturers, with specific election windows and dates (including January 1, 1994; and the election period January 1, 1997, through January 1, 2004, or rules starting after those dates depending on when a maker began assembling in Mexico). Cars not made domestically are treated as having the same fuel economy as the maker’s other non-domestic cars. A maker may ask the Transportation Secretary to approve a plan to have certain models counted as domestic for up to four model years (covering at most 150,000 cars per year) if those models will become domestically made within that period and meet conditions like at least 50% U.S./Canada value and timely import rules. The EPA must report its measurements and calculations to the Secretary of Transportation and work with that office.
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Transportation, Source: USLM XML via OLRC
Legislative History
Reference
Citation
49 U.S.C. § 32904
Title 49, Transportation
Last Updated
Sep 22, 2026
Release point: 119-110