A 1977 amendment to the Clean Air Act required gasoline additives to be substantially similar to those used in certifying vehicles to emission standards. EPA may grant a waiver to these requirements under certain circumstances. Ethanol has been granted two such waivers.

In 1978 a Clean Air Act waiver allowed the use of 10 volume percent ethanol in gasoline, known as gasohol or E10. Today, almost all gasoline are E10 blends. 

In June 2011, EPA approved blends of 15 volume percent ethanol in gasoline for use in model year 2001 and newer passenger cars, light-trucks and medium-duty vehicles.  

Learn more E15 partial waivers. 

Learn more about E15 regulations. 

Learn more about E15 misfueling mitigation plans. 

Learn more about E15 survey plans. 

Learn more about E10 waivers.