E85 FAQs


E85 flex fuel is a mixture of gasoline and ethanol, or ethyl alcohol. In the USA, it's made from corn biomass, plant materials (primarily corn), and other renewable sources.

There are several different types of flex fuel: E85, E50, E15, and E10 are the most common. The E represents “ethanol”, and the numeric value represents the percentage of ethanol in the mixture. For example, E85 contains up to 85% ethanol, while E10 contains up to 10% ethanol. At 100+ octane, E85 is the highest octane fuel on the market.

Yes. Flex fuels are renewable, and they're cleaner and more environmentally friendly than gasoline too. It starts with the fact that ethanol burns cleaner than gasoline - with few impurities, E85 almost fully combusts. Gasoline, on the other hand, often contains small amounts of heavy oils, sulfur, and other impurities that don't get completely burned off. Instead, they end up as soot in the air.

According to the EPA, a vehicle running on E85 produces roughly 50% fewer emissions than a vehicle burning regular gasoline. That means E85 is much better for the planet than gasoline.

If you’re wondering how to use flex fuel, it works the same as gasoline. If your vehicle is compatible with flex fuel (or if you have an eFlexFuel kit installed in your vehicle), you can fill up your fuel tank with E85. And if you have an eFlexFluel kit and there's no E85 available, you can always use regular gasoline. That's because eFlexFuel kits include an ethanol sensor that precisely determines the fuel mix, and the eFlexFuel kit optimizes the engine in real time.

NOTE: As long as you have a kit from eFlexFuel, you can even mix E85 with regular gasoline. eFlexFuel kits are capable of constantly measuring the ethanol content of your fuel, and then dynamically adjusting engine tuning for any blend of E85 and gas for maximum efficiency.

E85 flex fuel is available in many gas stations across the United States. Some gas stations advertise that they offer flex fuel. It will be sold at a pump just like gasoline, and labeled “E85” at the pump.

Want to find the closest E85 gas station? Head on over to our interactive map of E85 stations across the US and enter your location to see the nearest station that offers E85!

E85 can give your vehicle more horsepower, but the exact amount depends on your specific engine. However, you will only see performance improvements if your engine is properly tuned. All eFlexFuel kits will make sure your engine is tuned to run on E85. However, only our eFlexPlus and eFlexPro offer performance engine tunes.

With our eFlexPro kit and free eFlexTuner tuning software you can create performance engine tunes (which you can load and customize using our tuning software or mobile app), and you can see horsepower gains as high as 20%.

The main reason that E85 boosts engine horsepower and torque is that high-octane ethanol can resist knocking better than gasoline and has a cooling effect on the intake and combustion chamber. Here's the more detailed explanation:

  • E85 fuel has a higher octane rating than any pump gasoline. This means that with E85 and eFlexFuel the vehicle ECU does not need to retard ignition or lower the boost pressure.
  • E85 fuel has a faster ignition time and flame propagation than gasoline. This leads to a higher cylinder pressure, as well as increased engine torque and power, exceeding even +15% gains. The increased exhaust gas flow allows turbos to spool quicker.
  • Ethanol has over 1/3rd of oxygen by mass, which is higher than in oxygenated race fuels, where the levels are below 1/6th of oxygen by mass. This enables higher injection volumes per ignition, which means even more power. Ethanol evaporation absorbs more heat from the intake air. This way the engine has a better charge cooling effect and runs cooler when compared to gasoline..
  • Cooler air is denser, and denser air allows for more fuel combustion.
  • The more fuel you burn, the more power you can make.

Basically, ethanol acts sort of like an intercooler on a turbocharged engine: It makes the air going into the engine cooler and allows for more fuel to be burned, therefore producing more engine power.

E85 is a blend of gasoline and ethanol. Ethanol is derived from many different raw materials, the most common of which is corn:

  1. The raw material (corn, sugar cane, and various biomass) is collected.
  2. The raw material is put through a grinding process to extract the sugar.
  3. The sugar is fed to microbes, which produce ethanol and carbon dioxide.
  4. The ethanol is purified to reach the right consistency.
  5. The ethanol is added to regular gasoline until the right balance is achieved.

Some large-scale E85 manufacturers use the wet-milling process to produce E85. It produces the same end result, which is then mixed with gasoline. . The ethanol manufacturing process is improving all the time bringing the environmental impact down and in some instances ethanol is even made from industrial or food waste.

The E85 weight per gallon is slightly higher than the weight of regular gasoline. It’s usually 6.59 pounds per gallon. Regular gasoline weighs between 5.8 and 6.5 pounds per gallon.

Not really. Technically, E85 does not cause white smoke. However, because ethanol is not quite as energy dense as gasoline, more ethanol is burned during start-up than with gasoline. This means that more water is introduced to your exhaust system when running on E85 (remember, water is a byproduct of all combustion - gasoline and E85 alike).

Water is primarily the cause of white "smoke" at engine start, but that "white smoke" isn't smoke at all. It's steam.

NOTE: A coolant leak in your engine can also cause white smoke. If you see lots of white smoke coming out your vehicle's tailpipe, it's either cold outside (making all the steam in your engine exhaust very easy to see) or your vehicle has a coolant leak.

E85 doesn’t always make your car louder. Sometimes it changes the way your exhaust sounds, but most people don't notice any change.

Yes, there’s an E85 winter blend. The ethanol in flex fuel serves as an antifreeze agent for gasoline, so E85 doesn’t freeze. But flex fuel doesn’t warm up as quickly as gasoline does. That can be problematic in cold weather. That’s why E85 winter blends exist

Winter blends have lower amounts of ethanol. Gas stations switch to winter blends before cold weather hits. If in doubt, ask your gas station if the E85 available is a winter blend.

Usually, yes - but it depends on where you live.

If E85 is easy to find in your area, odds are good it will be much cheaper than premium gasoline, saving you money.

  • In most places in the US, a gallon of E85 costs less than a gallon of regular gas at the pump - and a LOT less than a gallon of premium gasoline.
  • However, when you burn E85 in your vehicle's engine, your fuel economy will decrease 15-25% (the exact amount varies based on engine, E85 blend, time of year, etc.)
  • If E85 costs at least 20% less than the gasoline you usually buy, it may save you money
  • If the E85 costs 30% less than the gasoline you usually buy, it will definitely save you some money

If you want to know how much money you can save on E85, check out our E85 fuel savings calculator. It will help you estimate your annual fuel savings based on how efficient your vehicle is currently, where you live, and how much you drive.

If you're wondering if you'll go thru a tank full of E85 faster than a tank of regular gasoline, the answer is yes. E85 does not contain as much chemical energy as gasoline, so you'll burn 15-25% more E85 per mile than you would gasoline.

But since E85 also burns cleaner and cooler, it's better for your engine because it dispels engine heat and provides more stable and cleaner combustion. As a result, your engine delivers more power and is exposed to less grime.

E85 runs cleaner, but does it clean your engine? The answer is yes. Ethanol is an excellent cleaner. It will remove deposits throughout the engine and in the fuel injectors left by dirty gas. If your vehicle is compatible with E85, and if you regularly use gasoline, it’s a good idea to run at least 1 or 2 tanks worth of E85 through your engine regularly just for the cleaning benefits.

An E85 tune is an engine fuel and timing "map" that makes it possible for your vehicle to run on E85. E85 tune is made to a specific ethanol content in the fuel, meaning that with an E85 tune the engine can only use E85 fuel with specific ethanol content. As in reality the ethanol content in E85 can vary from 51% to 83%, an E85 tune is seldom optimal and can be inconvenient. eFlexFuel kits are not an E85 tune. Instead, they offer full flex fuel capability meaning that the engine is always tuned to perfection for the fuel that you’re running, whether it’s E85, gas or any mix of the two. Besides offering full flex fuel capability, eFlexFuel kits come with preset driving modes or tunes for different driving environments that optimize the engine’s power and consumption. The Plus and Pro products even enable creating your own custom tunes and accessing them from the eFlexApp when driving.

There are several different kinds of driving modes available:

  • Our "Eco" tune, which is designed to maximize the efficiency of your vehicle's engine when operating on E85. Our eco tune is included with all of the eFlexFuel kits.
  • "Performance" tunes, of which we have two presets, are designed for a specific application - a tune with more low end torque will be great for towing or hauling, while a tune for maximum horsepower will be great for the race track.
  • "Custom" tunes, which allow the vehicle owner to adjust the fuel and timing map based on their vehicle's modifications and upgrades. With the eFlexPlus and eFlexPro kits, we include custom tuning software that allows both professionals and knowledgeable consumers to create custom E85 tunes based on specific modifications and dyno data.

A. No. Using E85 in your vehicle without an E85-specific engine tune can quickly ruin your engine. That's because more fuel is needed when E85 is used. If you were to try to run E85 in an engine that was tuned for gasoline, it would run lean. Running lean can lead to serious engine damage.

So, if you don't have a kit like ours or an E85 tune, you don't want to put E85 in your engine.

Installing one of our eFlexFuel Kit will take most people an hour or two. Only basic hand tools and a multimeter are needed, but it's a task that's best accomplished by someone with some basic repair and maintenance experience. Everything that’s needed for a DIY installation is included in the kit.

To install one of the eFlexFuel kits:

  • First install the ethanol flex fuel sensor in the fuel line. For this the kit comes with a fuel line disconnect tool and quick connectors that enable the safe installation of the ethanol sensor in either the vehicle’s original fuel line or to a fuel line that we supply.
  • Next, install the the wiring harness to the fuel injectors, connect the ground and place the temperature sensor within close proximity of the engine block
  • • Place the eFlexFuel control unit within the engine bay and connect it to the wiring harness

For more details, check out our full eFlexFuel installation guide.

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