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What is E85? A Complete Guide to Flex Fuel

By Michael O'Connor | January 17, 2023

What is E85 Gas?

E85, also called flex fuel, is a fuel blend that uses a mixture of ethanol and gasoline. Depending on the season, your region, and its availability, E85 fuel will be made up of anywhere between 51 and 85 percent ethanol, with the rest being traditional gasoline.

During the colder months in certain regions, the level of ethanol in E85 will be lower since the lower temperatures will make it harder for the fuel to ignite.

Almost all regular gas for vehicles contains a certain level of ethanol. However, it is usually at or around the 10-percent mark instead of the higher concentration of E85. This is done to help oxygenate the fuel and help it burn cleaner than the gasoline would be able to without it.

As the years go by and concern for the environment and the impact of vehicles grows, people are looking for alternatives to traditional internal combustion engines. There are more and more electric vehicles being offered on the market but in places where energy bills are high and charging stations are unavailable, this won’t always be the best option. That is why E85 and Flex Fuel vehicles are such an interesting option and why it is important to know what they are and how they can impact your driving life.

What is Ethanol?

Ethanol is a flammable liquid that is made from plant materials such as corn and other vegetables. It is an alcohol-based fuel and it has a characteristically wine-like scent and consistency. The plant materials used in its production are known collectively as biomass and they make it a renewable, relatively eco-friendly fuel for vehicles.

Ethanol has long been a favorite fuel for motorsports enthusiasts because it helps keep the engine cool when it is running at an incredibly high RPM. However, it also tends to burn much faster, which can decrease the fuel economy of a vehicle. Depending on your needs and what you generally use your car for, it may or may not be the right choice for you.

Pros of Flex Fuel:

E85 flex fuel is not nearly as common at fuel stations as regular gasoline and flex fuel vehicles, or FFVs, are not as widely manufactured as traditional vehicles. That being said, there are some major benefits to using E85 that can make seeking it out well worth it. Understanding some of the advantages of this ethanol-gasoline blend can help you figure out if it will be a good investment for you. If you have E85 stations in your area and you can get your hands on a car with the right fuel injection and software for the engine, it may be a good option.

Lower Dependence on Foreign Oil:
One of the major advantages of using flex fuel for your vehicle is the fact that it reduces dependence on foreign oil and fossil fuels produced in other parts of the world and imported to the United States. Ethanol fuel can easily be produced domestically, which has all kinds of geopolitical advantages. A combination of flexible fuel vehicles and electric cars on the road can have a huge impact when it comes to dependence on oil and the sustainability of driving in general. If these are issues that you are concerned about and E85 is available at fuel pumps in your area, an FFV could be a good choice for you.

Fewer Pollutants:
Perhaps the most important benefit of E85 and fuels with a high ethanol content is the fact that the emissions that come out of the tailpipe have far fewer pollutants. Flexible fuel has a higher ethanol content, which means that the exhaust has fewer hydrocarbons and other byproducts that can cause greenhouse gas emissions. Ethanol runs much cleaner due to the ingredients that go into its production. If you want to drive a vehicle that is not as tough on the environment as a traditional internal combustion engine but you don’t want to make the switch to electric, an FFV can help you walk that line without sacrificing horsepower.

Less Risk of Engine Knock:
Since ethanol has a higher octane rating, you are much less likely to develop a pre-ignition knock in your engine. Ethanol is more flammable and will burn as soon as it hits the ignition of the spark plug. High-ethanol fuel like E85 is much less likely to have a slow ignition, which is the source of most engine knocks. By using E85, you can be sure that your cylinders and other components of the fuel system will be protected from the pitfalls and risk of damage that come along with engine knocks and problems with the ignition of the fuel within the engine block.

Cons of Flex Fuel:

While there are certainly some benefits of using E85 flex fuel, the disadvantages should be taken into consideration as well. Any time you are exploring your options with an alternative fuel type, you need to think about how it might affect your ability to drive your car and the availability of that particular kind of fuel. Knowing what you can expect when it comes to the limitations of E85 can help you decide if a vehicle that uses it will be a good option for you. With careful consideration, you won’t find yourself stuck without the right kind of gas for your vehicle.

Limited to Certain Vehicles:
One of the problems with E85 is the fact that it will only work with certain vehicles. In 2023, only three automakers are offering flex-fuel-compatible vehicles: Chevrolet, Ford, and GMC. If you aren’t sure whether or not your car can accept flex fuel, be sure to check your owner's manual. Another way to check is to look at your vehicle’s gas cap. Cars that can accept flex fuel will have a yellow gas cap or a yellow plastic ring around the fuel intake. The next time you go to a gas station, check and see if these markers are on your car. FFVs can usually take either E85 or traditional gasoline, but it is important to read your manual and know for sure.

Lower Fuel Efficiency:
Perhaps the biggest disadvantage of using E85 in your car is the fact that it will reduce the fuel efficiency of the vehicle. Because higher octane fuels like E85 burn faster, they will reduce the MPG of your car and you may find yourself having to fill up more frequently than you would with a car that uses traditional gasoline. E85 is not immune to higher gas prices and if you are getting fewer miles out of every tank, it may not be worth it to make the switch. While high-octane fuels are generally better for the environment and will give better engine performance, most motorists are not too keen on the idea of having to fill up more than usual.

Harder to Find:
No matter how you look at it, E85 fuel is going to be harder to find than traditional gasoline. Because ethanol is primarily made of corn, E85 is fairly common in places that produce corn in abundance, such as the midwest. In regions like New England or the Pacific Northwest, you may find that it is difficult or impossible to find E85 at a filling station. Before you decide to purchase a vehicle that uses flex fuel, be sure to check on its availability in your area. Even though many of these vehicles can take both kinds of fuel, it is best to know whether or not you will be able to take advantage of this feature.

Availability of E85

One of the things that may make E85 less practical than traditional gasoline is the fact that it can sometimes be difficult to find. As of 2023, there are around 140,000 filling stations in the United States that sell E85 to the public. Minnesota has the highest concentration of these stations with 450 and Illinois has the second highest with 290. Some states, such as Maine, New Hampshire, and Rhode Island, don’t have any stations that sell flex fuel to the public.

Many gas stations will be reluctant to sell E85 due to the extra work and expense that comes with storing and producing it. E85 needs to be specifically blended and the pumps need to have specialized equipment to be able to bring it from the tanks to the pump. Flex fuel pumps also need special graphics and advertising, which can drive up costs for the stations. Because of these limitations and extra expenses, many stations will not carry E85.

Vehicles That Can Use Flex Fuel:

As of 2023, Ford, Chevrolet, and GMC are the only automakers that are producing new vehicles that can use E85 fuel.

According to the U.S. Department of Energy, the current models that can take it include:

  • Chevrolet Silverado 2WD
  • Chevrolet Silverado 4WD
  • Ford F150 2WD FFV
  • Ford F150 4WD FFV
  • GMC Sierra 2WD
  • GMC Sierra 4WD
  • Chevrolet Express 2500/3500
  • Ford Super Duty F250, F350, F450
  • Ford Transit 250/350 Cargo Van
  • GMC Savana 2500/3500

Final Thoughts

As gas prices go up and more people are thinking about their impact on the environment, many drivers are looking for ways to reduce their carbon footprint and change the way they drive. E85 fuel is an excellent alternative to traditional gasoline that has a lot of advantages as well as disadvantages. Knowing what E85 is and how it can make your vehicle more eco-friendly can help you decide if the trade-offs associated with it will be worth it and whether or not it is a good decision for you and your driving needs.