Ethanol
Ethanol is a renewable, domestically produced alcohol fuel made from plant material, such as corn, sugar cane, or grasses. Using ethanol can reduce oil dependence and greenhouse gas (GHG) emissions. Ethanol fuel use in the U.S. has increased dramatically from about 1.7 billion gallons in 2001 to more than 14 billion in 2023.1
E10 and E15
E10 and E15 are blends of ethanol and gasoline. The number after the "E" indicates the percentage of ethanol by volume.
Most of the gasoline sold in the U.S. contains up to 10% ethanol—the amount varies by region. All automakers approve blends up to E10 in their gasoline vehicles.
As of 2011, EPA began allowing the use of E15 in model year 2001 and newer gasoline vehicles.2 Pumps dispensing E15 must be labeled (see example). A vehicle's owner manual may indicate the maximum ethanol content recommended for it by the automaker.
Ethanol contains about one-third less energy than gasoline. So, vehicles will typically go 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on 100% gasoline.3
E85 (Flex Fuel)
E85, also called flex fuel, is an ethanol-gasoline blend containing 51% to 83% ethanol, depending on geography and season. Summer blends tend to have more ethanol while winter blends have less.4 E85 can be used in FFVs, which are specially designed to run on gasoline, E85, or any mixture of the two. FFVs are offered by several automakers. We provide a brief guide to help you determine if your vehicle can run on flex fuel.
MPG. Due to ethanol's lower energy content, FFVs operating on E85 get roughly 15% to 27% fewer miles per gallon than when operating on regular gasoline, depending on the ethanol content. Regular gasoline typically contains about 10% ethanol.5
Cost. The cost of E85 relative to gasoline or E10 can vary due to location and fluctuations in energy markets. E85 is typically cheaper per gallon than gasoline but slightly more expensive per mile.
Performance. Drivers should notice no performance loss when using E85. In fact, some FFVs perform better—have more torque and horsepower—running on E85 than on regular gasoline.6,7,8
Availability. E85 is sold at more than 4,400 filling stations in the U.S. View the Alternative Fueling Station Locator for service station locations.
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Alternative Fuels Data Center
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Environmental Protection Agency. E15: Frequently Asked Questions.
- EIA. 2024. Monthly Energy Review, June 2024. p. 181.
- EPA, Notice Of Decision Granting A Partial Waiver. "Partial Grant of Clean Air Act Waiver Application Submitted by Growth Energy To Increase the Allowable Ethanol Content of Gasoline to 15 Percent; Decision of the Administrator," Federal Register 76, no. 17 (January 26, 2011):4662.
- Knoll, K., B. West, W. Clark, R. Graves, J. Orban, S. Przesmitzki, and T. Theiss. 2009. Effects of Intermediate Ethanol Blends on Legacy Vehicles and Small Non-Road Engines, Report 1 – Updated
. NREL/TP-540-43543. National Renewable Energy Laboratory, Golden, Colorado, p. 3-3. - ASTM Standard D5798-11, "Standard Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines," ASTM International, West Conshohocken, PA, 2003, DOI: 10.1520/D5798-11, www.astm.org.
- The fuel economy difference between using E85 and gasoline is given as a range since E85 includes blends containing 51% to 83% ethanol:
- The lower bound (15% mpg decrease) is based on the difference in the energy content of a 51% ethanol blend and that of gasoline, which is typically 10% ethanol.
- The upper bound (27% mpg decrease) is based on the difference in official EPA fuel economy tests of recent-model FFVs operating on ethanol-free gasoline and operating on E85.
- General Motors. 2014 Chevrolet Silverado Specifications.
- Thomas, J. F., S. P. Huff, and B. H. West. 2012. Fuel Economy and Emissions of a Vehicle Equipped with an Aftermarket Flexible-Fuel Conversion Kit. ORNL/TM-2011/483. Oak Ridge National Laboratory, Oak Ridge, Tennessee.
- Thomas, J., B. West, and S. Huff. 2015. Effects of High-Octane Ethanol Blends on Four Legacy Flex-Fuel Vehicles, and a Turbocharged GDI Vehicle. ORNL/TM-2015/116. Oak Ridge National Laboratory, Oak Ridge, Tennessee.