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What is E85 Gas? Everything You Need To Know About Flex Fuel

By 12/19/2024 12:00pm
A gasoline pump that dispenses E85 Flex Fuel.

What Is Flex Fuel: E85 Quick Facts

  • E85 fuel is blended from about 85% ethanol and 15% gasoline.
  • Flex fuel vehicles can use E85 or regular unleaded; traditional gas engines cannot use E85 flex fuel.
  • E85 costs around 60 cents less per gallon than regular gas, but vehicles using it travel fewer miles per gallon.
  • E85 is not available at every filling station.

Vehicles that can run on flexible fuel, a blend of gasoline and ethanol, also known as “flex fuel,” started becoming popular in the 1990s. In turn, manufacturers began producing new cars that could use this biofuel blend. But many motorists know little about ethanol-blended gasoline labeled E85 at gas pumps.

Even some owners of flex-fuel vehicles, or FFVs, have questions about gasoline-ethanol blends. Read on to learn about flex fuel and whether you can use E85 or other blended gas in your vehicle.

What Is Flex Fuel?

Flexible fuel is the general term for a renewable and domestically produced alternative fuel that is gasoline blended with ethanol. Ethanol is made from a collection of plant materials, including corn. Most of the gas sold in the United States contains some ethanol. However, E85 for FFVs uses a higher percentage of ethanol. So, what is 85 gas?

Also known as flex fuel, E85 is a gasoline-ethanol blend containing between 51% to 85% ethanol, depending on the season and geographic region of the distributor. For example, E85 sold during colder months often has lower levels of ethanol to produce the vapor pressure necessary for starting in cold temperatures.

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Can My Car Use Flex Fuel?

Manufacturers make flex-fuel vehicles with modified internal combustion engines using traditional gasoline and ethanol blends, such as E85. A badge with “Flex-Fuel,” “FFV,” or “E85” on the rear of the vehicle may indicate it is compatible with the alternative fuel.

Having a yellow gas cap is a good indication that the car can use flex fuel. If the vehicle has a capless fuel filler, a yellow ring around the hole where the nozzle gets inserted signals E85 works for the vehicle.

Using any octane level of gasoline in a flex-fuel vehicle is acceptable. The sensors in an FFV detect whether the fuel is pure gasoline or 85% ethanol and make necessary changes for optimal fuel injection and timing of combustion.

Putting E85 in a car not designed for flexible fuel can be harmful. Always refer to the owner’s manual for specifications on fuel to use in your vehicle.

Can You Use Regular Gas in a Flex-Fuel Vehicle?

One benefit of flex-fuel vehicles is that they also are compatible with regular gasoline. FFV engines have sensors that detect the gasoline-ethanol ratio in the fuel and make adjustments for optimal performance.

Can You Use Flex-Fuel in a Regular Gas Car?

Flex-fuel, such as E85, can be used only in flex-fuel vehicles and will damage a traditional gasoline engine.

MORE: What Happens if You Put Diesel in a Gas Car?

Why Would I Use Flex Fuel?

Proponents of higher ethanol-gasoline blends cite lower greenhouse-gas emissions since flex fuel burns cleaner than pure gasoline, and its use reduces reliance on foreign oil. The main ingredient in processing ethanol is corn, a sustainable crop grown in the United States.

E85 costs less per gallon than regular gasoline, making it an attractive option. At this time, AAA reports the national average gas price for a gallon of E85 is $2.48 — about 57 cents less than a gallon of regular unleaded gas.

Flex Fuel Disadvantages

While the price per gallon of E85 is typically less than regular gas, FFVs using the ethanol-gasoline blend have lower fuel economy ratings. In some cases, the difference in mileage is close to 25%.

For example, a 2023 Ford F-150 2WD FFV pickup with a 3.3-liter 6-cylinder engine earns 21 combined mpg when using gasoline but only 16 combined mpg when using E85. Often, the lower price per gallon for E85 offsets the mileage loss.

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Availability of E85 and FFVs

Around 4,500 gas stations across the U.S. sell E85 flex fuel, mostly in corn-producing Eastern and Midwestern states. However, you can find vehicles compatible with E85 nationwide because those automobiles can also use traditional gasoline.

It’s unclear how many flex-fuel vehicles exist on the road today. One study found 21 million FFVs in the U.S. in 2017. More recently, some estimate more than 27 million vehicles are using flex fuel.

The number of new FFV offerings from manufacturers has decreased. The primary reason: Federal incentives for automakers shifted to those building electric vehicles.

Four automotive brands — Buick, Chevrolet, Ford, and GMC — offer FFVs in the 2025 model year. Flex-fuel compatibility may depend on specific trim levels or engine selection. Additionally, some models using E85 may be designated only for fleet sales.

According to the Renewable Fuels Association (RFA), more than 80 different models from eight manufacturers were available to consumers as recently as the model year 2015.

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Other Ethanol Blends

E10

About 98% of the gasoline sold in the U.S. contains ethanol, typically E10 with 10% ethanol and 90% gasoline.

E15

Another blend, E15 (with 15% ethanol), entered the market in 2011. Sales were restricted during the summer months, but EPA waivers since 2021 have permitted year-round E15 sales. The EPA allows E15 for light-duty vehicles built after 2000. Manufacturers approve using E15 in approximately 95% of their model-year-2024 automobiles, according to a review of owner’s manuals and warranty statements by the trade group RFA. The group says the blend is available at more than 2,800 gas stations and the average cost of E15 is about 25 cents per gallon less than regular unleaded.

E25

The RFA’s annual review indicates that E25 blends, containing up to 25% ethanol, are approved by the manufacturer for use in BMW and Mini vehicles. The 2024 Toyota GR Supra — developed with BMW — also allows E25.

E98

E98, 98% ethanol, is a popular fuel for some types of race cars.

If you’re trying to find the right car for you, check out our best cars and top 10 lists and the most fuel-efficient sedans.

Editor’s Note: This article has been updated since its initial publication.