Title 49 › SUBTITLE VI — MOTOR VEHICLE AND DRIVER PROGRAMS › PART C — INFORMATION, STANDARDS, AND REQUIREMENTS › CHAPTER 329 — AUTOMOBILE FUEL ECONOMY › § 32905
Fuel economy for cars that use alternative fuels is measured in different ways depending on the type and year. For cars that run only on an alternative liquid fuel made after model year 1992, the EPA uses the fuel’s energy content, and each gallon of the liquid alternative counts as 0.15 gallon of fuel. For cars that can use both an alternative fuel and gasoline or diesel made in model years 1993 through 2019, the EPA calculates a combined number as 1.0 divided by (0.5 ÷ gasoline/diesel economy + 0.5 ÷ alternative-fuel economy). If the alternative is B20, it is treated using the 0.15 gallon rule. For cars that run only on gaseous fuel made after model year 1992, 100 cubic feet of natural gas equals 0.823 gallon equivalent, and a gallon equivalent of gas counts as 0.15 gallon. Gaseous-fuel dual-fuel cars (1993–2019) use the same 1.0 ÷ (…) formula. For plug-in electric dual-fuel cars made after model year 2015, a manufacturer can ask the EPA to use a formula that weights gasoline use and electricity use by expected use; if not requested, the EPA uses the dual-fuel formula above. The EPA uses these measured values when it computes each manufacturer’s average fuel economy. To get the fuel-economy incentives in section 32906(a) and (b), each dual-fuel car made on or after September 1, 2006 must have a label on the fuel compartment saying it can run on the named alternative fuel and on gasoline or diesel.
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49 U.S.C. § 32905
Title 49, Transportation
Last Updated
Sep 22, 2026
Release point: 119-110