Wondering about using E85 fuel in your vehicle? E85 is a blend of 51-83 percent ethanol and gasoline, depending on the time of the year and location. There are almost 10 million flex fuel vehicles in the United States. In 2013, there were 162 models on the market from all of the major automakers. A 2007 study by Argonne National Laboratory found that lifecycle analysis for greenhouse gas emissions from ethanol to be 19-52 percent lower than gasoline, depending on method of production.

According to Michigan State University Extension, there are several ways to find out if your vehicle is a flex fuel vehicle and capable of burning E85. Flex fuel vehicles manufactured in 2008 or newer (2006 for GM) have a yellow gas cap. You will find a label on the fuel door indicating it is flex fuel. Most auto companies attach badges on the side or rear of the vehicle that say Flex Fuel. Your owner’s manual will indicate what type of fuel your vehicle burns. Finally, web sites like the U.S. Department of Energy’s Alternative Fuels Data Center or www.fueleconomy.gov can identify flex fuel vehicles using the VIN.

Since ethanol has higher octane than gasoline, oil companies can mix subpar gasoline with ethanol so that the resulting mixture contains the required octane level at the pump. But what does octane do? Octane reduces the occurrence of engine “knock.” In the combustion chamber, fuel and air are ignited, driving the piston down and producing power to the crankshaft. A valve opens, allowing more fuel and air mixture to enter the combustion chamber. As the piston comes back up, it compresses the fuel/air mixture, then the spark plug ignites the mixture, driving the piston back down. Engine knock is when the fuel/air mixture prematurely ignites before the piston has reached the top of the chamber.

Engine knock reduces engine performance and creates a potential risk for serious engine damage. Engine knock occurs less frequently with higher octane fuel mixtures. The high level of octane in ethanol reduces engine knock and allows for higher fuel and air compression in the combustion chamber without premature ignition. The compression in nearly all standard engines is designed for gasoline rather than E85. Fuel mileage would be increased if the compression of the engine was designed to burn E85.

One of the factors influencing demand and consumption of E85 fuels is fuel economy. E85 blends will generally get 15-25 percent less miles per gallon than regular gasoline. Engine and vehicle performance is not reduced, but since there is less energy (BTU’s) per gallon of ethanol, it takes more E85 to make the same trip. To compare the two fuels, one must calculate the cost per mile. For example, let’s say that regular unleaded gasoline is selling for $3.85 and E85 is selling for $2.85 per gallon. After burning a tank or two of E85, you determine that your vehicle gets 28 miles per gallon on gasoline and 22 miles per gallon on E85. Your cost per mile for gasoline is 13.75 cents ($3.85 divided by 28 miles per gallon) and 12.95 cents ($2.85 divided by 22 miles per gallon). Even though you get less fuel economy with E85, your cost per mile driven is lower.

So how do you find E85 for $1 per gallon less than gasoline? The Yellow Hose campaign is designed to help you find gas station pumps that sell E85 for at least a dollar under the current gasoline price. There are currently 29 stations in Michigan that participate. Visit www.yellowhose.com to find the nearest station and when you pull into the gas station, look for the pump with a bright yellow hose. There is also a handy calculator on the website to help you figure out the cost savings annually for your vehicle.

The U.S. Department of Energy keeps a database of ethanol fueling stations. There are currently 2,389 stations in the United States that sell E85. You can type your zip code and search for stations near you at their Alternative Fuels Data Center website.