Title 49 › Subtitle SUBTITLE VI— MOTOR VEHICLE AND DRIVER PROGRAMS › Part C— INFORMATION, STANDARDS, AND REQUIREMENTS › Chapter 329— AUTOMOBILE FUEL ECONOMY › § 32905
EPA must use special ways to figure fuel economy for cars that run on alternative fuels. For cars built only to run on a liquid alternative fuel after model year 1992, EPA counts fuel economy using the fuel’s energy content and treats one gallon of that liquid as 0.15 gallon of fuel. For cars made to run on both gasoline (or diesel) and an alternative liquid fuel in model years 1993 through 2019, EPA calculates fuel economy by using a formula that combines the gasoline fuel economy and the alternative-fuel fuel economy equally (1.0 divided by the sum of 0.5 divided by each fuel’s measured economy). B20 is treated as containing 0.15 gallon of fuel. For cars that use gaseous fuels only after model year 1992, EPA uses the gas fuel’s energy content. One hundred cubic feet of natural gas equals 0.823 gallon equivalent. The Secretary of Transportation sets equivalents for other gases, and each gallon equivalent is treated as 0.15 gallon of fuel. For gaseous dual-fuel cars in model years 1993 through 2019, EPA uses the same equal-part formula that combines gasoline and gaseous fuel economy. For dual-fuel cars after model year 2015 that can also plug in for electric driving, the manufacturer can ask EPA to use a different weighted formula based on how often the car will use gasoline versus electricity; if the manufacturer does not ask, EPA uses the earlier dual-fuel formula. EPA must use these measured values when it computes a maker’s average fuel economy. Dual-fuel cars made on or after September 1, 2006 must have a label on the fuel filler saying they can run on the stated alternative fuel and on gasoline or diesel.
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Citation
49 U.S.C. § 32905
Title 49 — Transportation
Last Updated
Apr 5, 2026
Release point: 119-73not60