Will E85 save me money?

At its current price per gallon, E85 doesn't save you money, and it might cost you more. E85 typically sells for 10 to 30 cents less per gallon than gasoline, depending on your region. However, E85 produces 72 percent as much energy per gallon as gasoline, so you burn more of it per mile — 28 percent more, in theory. This affects your mileage.

For example, the flex-fuel Chevrolet Impala equipped with a 3.5-liter V-6 engine gets an EPA-estimated 23/31 mpg (city/highway) on gasoline and 16/21 mpg when burning E85. The acceleration is pretty much the same, but the car's range is shortened. In other words, you'll be filling the tank more often when using E85.

Do the math and you'll discover that E85 must be priced roughly 28 percent less than gas just to break even. For example, if gasoline is $3 per gallon, E85 would have to be priced below $2.16 per gallon.

Ethanol has a lower energy content than gasoline. That means that about one-third more ethanol is required to travel the same distance as on gasoline. But other ethanol fuel characteristics, including a high octane rating, result in increased engine efficiency and performance.

The 15 percent gasoline used to formulate E85 is to assure cold weather engine starting and to enhance flame luminosity in case of fire. In low-percentage blends with gasoline, ethanol results in increased vapor pressure, which can be adjusted for in the fuel formulation process and/or controlled with on-board vehicle systems. All gasoline vehicles in use in the U.S. today can accept gasoline blended with up to 10 percent ethanol (sometimes called gasohol). Flexible Fuel Vehicles (VVFs) are cars and trucks that can use any level of ethanol up to 85 percent. They're built with special fuel system components designed to be compatible with higher ethanol concentrations.