Skip to main content


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 emissions. Ethanol fuel use in the U.S. has increased dramatically from about 1.7 billion gallons in 2001 to about 13.2 billion in 2013.1

E10 and E15

Label required on pumps that dispense E15. Label reads as follows: ATTENTION. E15, up to 15% ethanol. Use only in (1) 2001 and newer passenger vehicles (2) Flex-fuel vehicles. Don't use in other vehicles, boats or gasoline-powered equipment. It may cause damage and is prohibited by Federal law.

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—and all auto manufacturers 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). The vehicle owner's manual may indicate the manufacturer's maximum recommended ethanol content.

Since ethanol contains about two-thirds as much energy as gasoline, 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 vehicle manufacturers, and 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 30% fewer miles per gallon than when operating on regular gasoline, which 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. Though typically cheaper per-gallon than gasoline, it is often slightly more expensive on a cost-per-mile basis.

Performance. Drivers should notice no degradation in performance when fueling with E85. In fact, some FFVs perform better—generate more torque and horsepower—running on E85 than on gasoline or E10.6,7

Availability. More than 2,300 filling stations in the U.S. sell E85. Visit the Alternative Fueling Station Locator for service station locations.

Advantages & Disadvantages of E85
Advantages Disadvantages
  • Domestically produced, reducing use of imported petroleum
  • Lower emissions of some air pollutants
  • More resistant to engine knock
  • Added vehicle cost is negligible
  • Can only be used in flex-fuel vehicles
  • Lower energy content, resulting in fewer miles per gallon
  • Limited availability

MotorWeek Videos

MotorWeek segments provided by Maryland Public Television

Ethanol & Classic Cars

TranscriptAdobe Acrobat Icon

E85 Conversions

TranscriptAdobe Acrobat Icon

Ethanol Preferred by Indy Racing


American Le Mans: Green Racing

TranscriptAdobe Acrobat Icon

More Information

Fuel Economy Information for Ethanol Flexible Fuel Vehicles - Find a Car

Alternative Fuels and Advanced Vehicles Data Center (U.S. Department of Energy)

Environmental Protection Agency (EPA). E15: Frequently Asked Questions.

View Data Sources...
  1. EIA. 2014. Monthly Energy Review, August 2014. p. 141.
  2. 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.
  3. Knoll, Keith, Brian West, Wendy Clark, Ronald Graves, John Orban, Steve Przesmitzki, and Timothy Theiss. 2009. Effects of Intermediate Ethanol Blends on Legacy Vehicles and Small Non-Road Engines, Report 1 – UpdatedAdobe Acrobat Icon. NREL/TP-540-43543. National Renewable Energy Laboratory, Golden, Colorado, p. 3-3.
  4. 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,
  5. The fuel economy difference between using E85 and gasoline is presented as a range since E85 includes blends containing from 51% to 83% ethanol:

    • The lower bound (15% fuel economy decrease) is based on the difference in the energy content of a 51% ethanol blend and that of gasoline, which typically contains about 10% ethanol.
    • The upper bound (30% fuel economy decrease) is based on the difference in EPA fuel economy ratings of recent-model FFVs operating on gasoline and operating on E85.
  6. General Motors. 2014 Chevrolet Silverado Specifications.
  7. Thomas, John F., Shean P. Huff, and B. H. West. 2012. Fuel Economy and Emissions of a Vehicle Equipped with an Aftermarket Flexible-Fuel Conversion KitAdobe Acrobat Icon. ORNL/TM-2011/483. Oak Ridge National Laboratory, Oak Ridge, TN.