How much ethanol is in regular gasoline?

Regular gasoline in the United States typically contains up to 10% ethanol, also known as E10. This means that 10% of the fuel is ethanol and the remaining 90% is gasoline. Ethanol is a renewable fuel that is produced by fermenting plant materials such as corn, sugar cane, or grains. It is added to gasoline to reduce its environmental impact and to increase its octane rating, which improves engine performance.