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What is E85 Gas (Flex Fuel) and Should I Use It?

By Jason Collins | March 22, 2022

What is Flex-Fuel?

Flexible fuel (or flex fuel and E85) is an alternative type of regular gas that has a higher amount of ethanol mixed with the gasoline. E85 gas is made up of between 51% and 83% ethanol blended with gasoline.

Regular gasoline in the U.S. is typically E10, which means it contains 10% ethanol and isn't a flex-fuel.

The exact ratio of E85 ethanol depends on the location and season. In summer, for instance, producers add more ethanol to the ethanol-gasoline blend.

Benefits to E85/flex fuel include it being cheaper than comparable gas, less reliance on foreign oil, it's cleaner-burning. Downsides, meanwhile, include a significant use of corn crops, potentially worse fuel economy, and potential engine wear without proper maintenance.

What does flex-fuel mean for motorists? If you are looking for a more environmentally-friendly, fuel-efficient vehicle as your next car purchase, then flex-fuel is a term worth keeping an eye out for, especially since there are nearly 21 million FFVs on U.S. roads.

Over recent years, you have most likely heard increasingly more about flex-fuel and flex-fuel vehicles. You may have also noticed the E85 label at the gas pumps and wondered what fuel that was. Flexible fuel or E85 is the general term used for a renewable and domestically produced alternative fuel made up of a gasoline-ethanol blend.

The Advantages of Flex-Fuel

Below are some of the benefits of E85 flex-fuel and why you may consider switching from regular gas to flex-fuel.

Fewer Pollutants Released into the Atmosphere:
According to studies, more Americans today are concerned about the effects of their car's fuel consumption on the environment. Ethanol burns faster than regular gasoline, which means flex-fuel vehicles are more environmentally friendly because they emit fewer toxic emissions and greenhouse gases into the air. Ethanol also burns cleaner and with less carbon monoxide than gasoline.

Less Dependence on Foreign Oil:
Ethanol fuel is a sustainably produced fuel product made from a collection of plant materials such as corn and cane sugar. This makes flex-fuel a better alternative to foreign oil.

The U.S. government is actively trying to encourage the production and sale of E85 flex-fuel by providing subsidies, especially to the corn producers in the Midwest. By fostering the domestic production of ethanol, the country has less dependence on foreign oil providers.

Improved Performance:
Some people may argue that using an alternative fuel mixture can negatively affect your vehicle's overall performance; however, it can actually have the opposite effect. FFVs don't experience a loss in performance when fueled with E85 fuel; contrary to the argument, some have reported an increase in horsepower and torque.

Higher Resistance to Engine Knocking:
Engine knock, or pinging, happens when a separate pocket of air-fuel mixture ignites after the ignition spark has ignited the air-fuel mixture in the engine's combustion chamber. Engine knocking can cause severe damage to your car's engine, but motorists can prevent it by using the correct octane-rated fuel.

The octane rating of fuel measures its ability to resist engine knocking. Fuel with a higher octane rating (such as E85 fuel) has a higher resistance to engine knocking than a low octane fuel with lower ethanol content.

High octane fuels also allow for advanced ignition timing, which means the spark is fired long before the piston reaches dead center on the compression stroke. This also helps build resistance against engine knocking.

Tax Credits:
Car owners who own flex-fuel cars receive tax credits. This benefit means they can significantly reduce or even eliminate their tax obligations.

Lower Fuel Cost Per Gallon:
Flex-fuel offers a lower cost per gallon compared to gasoline. The national average for October 2021 was $2.73 per gallon of E85 flex-fuel. During the same period, gasoline was $3.25 per gallon.

Burning Facility:
One of the biggest benefits of a flex-fuel vehicle is that it can burn whatever proportion of fuel mixture is available in its combustion chamber. FFVs have specialized electronic sensors that gauge the fuel mixture blend, while the microprocessors adjust the fuel injection and the timing.

Disadvantages of Flex-Fuel

While weighing up the benefits of flex-fuel, it is important to explore the disadvantages too. Below are some of the cons of using flexible fuel.

Sole Crop Use:
Even though flex-fuel is under sustainable production, the production comes with a downside; the corn crops it's made from become a dedicated resource for producing flex-fuel only. This means that the price of animal feed could potentially increase. It is also important to remember that corn is susceptible to adverse weather conditions, such as drought, flooding, and disease. This could be problematic for the price of corn during poor harvests.

Possible Engine Damage:
Ethanol absorbs dirt quickly, which can cause corrosion and damage to your engine without regular maintenance.

Lower Fuel Economy Ratings:
Flex-fuel is likely to decrease the fuel economy of a vehicle using it. Ethanol raises the octane level of a vehicle slightly, which would, in theory, improve gas mileage. However, ethanol has less energy than regular gasoline, which means that about 1.5 times more ethanol is needed to have the same energy as gas. In the end, some research shows that this equals similar gas mileage, while other research has ethanol coming up short.

For the consumer, one thing to consider is that ethanol typically costs less than gasoline, so the expense of reduced gas mileage could potentially be mitigated that way. It's also worth noting that ethanol is routinely added to regular gasoline's fall/winter blends for non-flex-fuel vehicles to raise the octane.

For example, let's look at a 2021 Ford F-150 pickup FFV with a 3.3-liter 6-cylinder engine. It earns an EPA rating of 21 mpg combined when it only uses gasoline. When using E85, it earns an EPA rating of 16 mpg combined. The lower price per gallon of E85 fuel may help offset the mileage loss.

Not Readily Available in Some Areas:
While its popularity is gaining momentum with more fuel stations offering E85 fuel, there are still some areas in the U.S. where E85 flex-fuel is not readily available. Fortunately, modern FFVs can use any combination of gasoline and ethanol. The sensors will detect the fuel blend and make the necessary changes.

Flexible Fuel Vehicles

Flexible fuel vehicles (FFVs) have an internal combustion engine designed to operate on more than one fuel type. Other than a few modifications to the car's engine and fuel system, and a different powertrain calibration, flex-fuel vehicles are almost identical to pure gasoline cars.

The Ford F-150 is an excellent example of a flex-fuel car since it is available with flex-fuel powertrains, including the 3.3-liter and 5.0-liter engines. To accommodate the E85 fuel mixture, flex-fuel F-150s have unique fuel lines and fuel injectors. Their fuel system is lined with a nickel coating on the inside diameter of the fuel lines. The Ford F-150 also has a higher volume fuel pump and fuel delivery modules with aluminum rotors.

How to Identify a Flex-fuel Vehicle

To determine whether you have a flex-fuel car, look for these three things:

  • Badges on the exterior of the vehicle with "Flex-Fuel," "FFV," or "E85". Sometimes you may find a badge on the inside of your FFV.
  • A label on the inside of the fuel door.
  • A yellow ring around the fuel filler or a yellow gas cap.
  • You could also consult your owner's manual.

Current Flex-Fuel Vehicles

These are a few examples of new vehicles with an FFV option:

  • 2022 Chevrolet Silverado
  • 2022 Ford Explorer
  • 2022 Ford F-150
  • 2022 Toyota Tundra
  • 2022 Ford Transit Connect Wagon / Van
  • 2022 GMC Sierra

Flex Fuel Details and History:

The Renewable Fuels Association, a trade group for the ethanol industry, uses the term "flexible-fuel" to represent the fuel itself and calls anything that's more than 15 percent and less than 83 percent ethanol flex-fuel. However, the Department of Energy approved E15 (fuel containing 15% ethanol) for use in all vehicles of the model year 2001 and newer, including those not designated as FFVs.

Other than gasoline, ethanol or methanol are the prime ingredients in flex-fuel. Methanol is also known as wood alcohol and methyl alcohol. It is produced through the destructive distillation of wood and is generally less popular than ethanol as a fuel additive.

Pure ethanol is essentially grain alcohol, and it is primarily made from corn in the United States. Because ethanol is a corn-based product, E85 gas is more readily available in the Midwest region of the U.S. and less available in other areas like New England and the Pacific Northwest. According to the U.S. Department of Energy, there are approximately 3300 E85 gas stations available across 42 states that are available to the public. E85 fuel is available outside of the U.S.; however, ethanol producers often have to use an alternative to corn crops. In Brazil, for example, sugar cane is a prominent source of ethanol.

By law, and according to the ASTM (the American Society for Testing and Materials), fuel pumps marked "E85" must only dispense fuel mixtures containing between 51 and 83 percent ethanol in gasoline. The pump octane number of E85 is usually 110, instead of gasoline's 84 to 93 octane ratings, which can withstand more compression before engine knocking or auto-igniting.