Ethanol is a renewable fuel made from plant materials called biomass which is then converted to ethanol. While ethanol is typically associated with corn, ethanol can also be made from various cellulosic materials including wood and grass. The ethanol is transported to a fuel terminal to be blended with gasoline and distributed to fueling stations. 

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Ethanol is mixed with gasoline to form various blends including E10 (10% ethanol, 90% gasoline), E15 (15% ethanol, 85% gasoline), and E85 (85% ethanol, 15% gasoline), also known as flex fuel. 

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Flexible fuel vehicles (FFVs) are vehicles that are adapted to handle fuel that is primarily ethanol, which results in extra oxygen during the combustion process. At present, there are more than 17 million flex fuel vehicles in the United States.