E15-E20: Intermediate Ethanol Blends

Intermediate ethanol blends have an ethanol content greater than 10% and less than 85%. Commonly considered blends include E15 (15% ethanol, 85% gasoline) and E20 (20% ethanol, 80% gasoline). Fueling large numbers of vehicles with intermediate blends could provide similar benefits as fueling with low-level blends while increasing gasoline displacement and utilizing the nation's rapidly increasing ethanol production.

However, intermediate ethanol blends cannot yet be used legally in standard (non-flexible fuel) vehicles. For this to happen, the U.S. Environmental Protection Agency (EPA) must approve a waiver to the Clean Air Act, classifying the blends as "substantially similar" to gasoline. Research on intermediate blends is underway, which could lead to a waiver application to the EPA.

Intermediate blends can be used today in flexible fuel vehicles but do not qualify as alternative fuels under the Energy Policy Act of 1992 (EPAct). Some fueling stations currently use "blender pumps"—fuel dispensers that can create a variety of ethanol blends by mixing E10 with E85. The resulting intermediate blends can be used legally in flexible fuel vehicles but not in standard vehicles.