What is Ethanol 85?

Mary McMahon
Mary McMahon

Ethanol 85 or E85 is a fuel which blends up to 85% ethanol with gasoline. This type of fuel can be used in flexible fuel cars which are designed to run on blends of gasoline and ethanol. Use of E85 has been promoted as an alternative to fossil fuels which could reduce dependence on oil-producing nations for energy supplies, although there are some problems with this fuel product which must be addressed. Availability of ethanol 85 varies, depending on where one lives; the American Midwest, for example, has a number of sources for this fuel, while people in Canada may have more trouble getting it.

In the U.S., some cars can run on a fuel blend that is 85% ethanol and 15% gasoline.
In the U.S., some cars can run on a fuel blend that is 85% ethanol and 15% gasoline.

This fuel has a higher octane rating, which can contribute to increased efficiency. However, pure gasoline may not work effectively in the engine of a flex fuel vehicle which is designed to run on ethanol concentrations as high as 85%, which can be a problem when E85 is not available. Furthermore, like other high octane fuels, ethanol 85 delivers less miles (or kilometers) per gallon (or liter) than other fuels, which means that people can actually end up spending more on fuel with E85 than with conventional gasoline, depending on fuel prices.

This fuel also requires special retrofitting of an engine and its fuel system. Several car companies make flex fuel vehicles which can run on ethanol 85 or other ethanol/gasoline blends, including cars, light trucks, buses, and heavy trucks. In other cases, it may be necessary to convert a vehicle so that it can accept this fuel. Using ethanol 85 in a vehicle which is not equipped for it can have some unpleasant results, including damage to the fuel lines.

Sourcing of ethanol has also been raised as a concern by people who are troubled about the use of ethanol 85. Ethanol is a biofuel, which initially sounds appealing because it is a renewable resource. However, some base materials used for biofuels are very inefficient, and a few types of biomass used for ethanol production are actually so inefficient that more fuel is expended than is produced, and this is a serious problem. Some critics are also concerned about the food versus fuel debate, which centers around the idea that certain countries may be replacing the production of food with the production of fuel.

AGE 85 or aviation grade ethanol 85 is a version of ethanol 85 which is designed for use in aircraft. Aviation fuels need to meet some very specific standards which have made AGE 85 a tough sell to the aviation industry.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@Logicfest -- an even bigger problem is that some companies have grown lazy on alternative fuel research because of the availability of ethanol. If our goal is to be completely free of foreign oil or develop something to power engines with other than gasoline, ethanol won't solve those problems. You still have to have petroleum to make E85 work.


One of the main problems with this stuff is that farmers start growing crops for ethanol production instead of fuel. Corn, for example. If a bunch of farmers start growing corn for ethanol production instead of food, then the price of corn for human consumption will go up because of demand for the grain, the shortage of corn grown for people, etc.

That was already a problem because ethanol is a common fuel additive. Creating E85 fuel has only made that problem worse.


A major problem with E85 is actually finding a gas station that sells it. There are apps that will direct you to them, but you will probably have trouble running across those stations at all if you happen to live in a rural area.

By the way, most flex fuel engines have no problem with pure gasoline. In fact, your fuel economy will increase by using regular unleaded in them. Those engines wouldn't be very flexible otherwise. Still, check your owner's manual to see if running anything but E85 is harmful.

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