How much ethanol is in gasoline and how does it affect fuel economy?

In 2011, the 133.93 billion gallons of gasoline (3.19 billion barrels) consumed in the United States contained about 12.87 billion gallons of ethanol, accounting for 9% of the volume of gasoline consumed.

Most of the gasoline now sold has some ethanol in it, but the exact amount in the gasoline you buy varies by region. In general it will not exceed 10% by volume. Gasoline with 10% ethanol content by volume is called E10 and with 15% ethanol is called E15.  E85 is 85% ethanol and 15% gasoline.

The energy content of ethanol is about 33% less than "pure" gasoline, although this varies depending on the amount of denaturant that is added to the ethanol.  Thus, vehicle mileage may decrease by up to 3.3% when using E10.

All gasoline vehicles can use E10, but currently you need a light-duty vehicle with a model year of 2001 or greater to use E15, and a "flex-fuel" vehicle to use gasoline with an ethanol content greater than E15.  Most of the gasoline with more than 10% ethanol is sold in the Midwest.

Learn more:

Ethanol Blend Wall: Are We There Yet?

Gasoline with higher ethanol content getting closer to U.S. drivers' fuel tanks

Last updated: July 20, 2012

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