In the United States, one out of every eight gallons of gasoline sold contains ethanol. Most of this ethanol is purchased as blends of 10% ethanol and 90% gasoline, known as gasohol or E10, and is used as an octane enhancer to improve air quality.
E85 is an alcohol fuel mixture of 85% ethanol and 15% gasoline, by volume.
E85 is used in engines modified to accept higher concentrations of ethanol. Such flexible-fuel engines are designed to run on any mixture of gasoline or ethanol with up to 85% ethanol by volume.