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Use of Ethanol

Ethanol as a transportation fuel

Did you know?

The Ford Model T had an engine capable of running on either gasoline or ethanol.

Nearly all gasoline sold in the United States contains ethanol.

gasoline pump

Source: Stock photography (copyrighted)

Pump label required for E15.

E15 label

Source: U.S. Environmental Protection Agency (public domain)

E10 and E15

Ethanol can be a transportation fuel used as a partial replacement for gasoline.

Most of the gasoline now sold in the United States contains some ethanol. The exact amount varies by region. In general, the ethanol content of motor gasoline does not exceed 10% by volume. Gasoline with 10% ethanol content is referred to as E10, and gasoline with 15% ethanol content is called E15. All gasoline vehicles can use E10. Currently, only light-duty vehicles with a model year 2001 or greater can use E15.

The U.S. Environmental Protection Agency (EPA) is responsible for developing and implementing the U.S. Renewable Fuel Standard (RFS) to ensure that transportation fuel sold in the United States contains a minimum volume of renewable fuel. EPA is developing processes and procedures for how ethanol blends greater than E10 can be sold at retail.


E85 is an alternative fuel that contains up to 85% ethanol. Although E85 is used mainly in the Midwest, there are about 2,600 public E85 fueling stations located around the country. Only flexible-fuel vehicles can use E85.

Flexible-fuel vehicles: Flexible-fuel (flex-fuel) vehicles can run on any mixture of ethanol and gasoline up to E85. Although there are more than 100 million flex-fuel vehicles in the Unites States, only about 10% of them use E85.

Last updated: February 1, 2016

Ethanol is added to gasoline

Typical E85 badge used to identify flexible fuel vehicles in the United States
Typical E85 badge used to identify flexible-fuel vehicles in the United States

Source: Stock photography (copyrighted)

Most of the gasoline in the United States is blended with some amount of ethanol. These blends are named by their ethanol content. For example, a blend of 10% ethanol and 90% gasoline (by volume) is known as E10 gasoline. In 2015, about 14 billion gallons of ethanol were added to gasoline in the United States, nearly all in mixtures of E10 or less.

Any gasoline-powered engine in the United States can use E10, but only specific types of vehicles can use mixtures containing more than 10% ethanol. Because ethanol contains approximately 67% of the energy content of gasoline per gallon, use of ethanol blends results in decreased vehicle fuel economy (miles traveled per gallon). Vehicle fuel economy may decrease by about 3% when using E10. Despite this reduced gas mileage, high crude oil prices and government incentives and mandates have resulted in increased ethanol consumption.

Government policies help boost ethanol use

Ethanol was one of the first automotive fuels in the United States. With the exception of the two world wars, only small amounts of fuel ethanol were used until the 1970s. The oil embargo against the United States by major oil producers in the Middle East in 1973 and increases in oil prices in the late 1970s and early 1980s spurred interest in fuel ethanol as a way to reduce U.S. oil imports that had to be refined into gasoline. Various state and federal government policies and programs dating as far back as the mid-1970s have led to increased ethanol use in gasoline. About two million gallons of fuel ethanol were used in 1981, and about 14 billion gallons were used in 2015. In 2011, with the U.S. ethanol industry well established and because of concerns about the federal budget deficit, the U.S. Congress let a 45-cent-per-gallon tax credit for ethanol blenders and a 54-cent-per-gallon tariff on ethanol imports expire at the end of 2011. The tax credit for blenders had been available for three decades.

Ethanol use increased significantly in 2002 as states began to ban the use of the gasoline oxygenate known as methyl tertiary butyl ether (MTBE) because of concerns that it contaminated groundwater. Ethanol quickly replaced MTBE as a gasoline oxygenate across the country. Ethanol use also increased after Congress passed the Renewable Fuel Standard (RFS) requirements under the Energy Policy Act of 2005 and then expanded and extended the RFS under the Energy Independence and Security Act of 2007. The RFS requires U.S. renewable fuel use to increase annually until it reaches 36 billion gallons by 2022.

The RFS targets were based on the assumption that U.S. gasoline consumption will increase over time so more ethanol can be blended with gasoline without hitting the E10 blend wall. The blend wall is the maximum ethanol blend that will not damage the engines and fuel systems of vehicles that can't use a gasoline-ethanol blend higher than E10. Gasoline consumption in 2012, 2013, and 2014 was close to the E10 blend wall level.

The U.S. Environmental Protection Agency (EPA) administers the Renewable Fuel Standard and is developing processes and procedures on how ethanol blends greater than E10 can be sold. The EPA ruled in January 2011 that E15 can be used in cars and light trucks built after the 2001 model year without causing damage to the engine and fuel system. The EPA also approved a new E15 label for gasoline pumps so consumers know what fuel they are buying.

Flexible fuel vehicles can run on fuel blends up to E85

Although almost any regular gasoline car can run on blends of ethanol up to E10, only flexible fuel vehicles (FFV) can operate with E85 gasoline—a blend containing between 51% and 83% ethanol by volume. Flexible fuel vehicles are currently available from every major U.S. automobile manufacturer at no extra cost and are almost identical to regular gasoline vehicles, with the exception of a few modifications to the fuel system and minor engine components. About 2,800 fueling stations in the United States sell E85 to the public.

Last updated: August 12, 2016