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What is Flex-Fuel? – Advantages and disadvantages

As everyone looks to save money on fuel and explore other modes of transportation, the flex-fuel vehicle has become more popular. What is a flex-fuel vehicle and how could it help you?

In this guide, we explore the purpose of flex fuel and show you which vehicles can use E85. We also discuss the pros and cons of this alternative fuel. At the end of our guide, we talk about the different ethanol-containing blends and the purpose of each.

What is flexible fuel?

Flex Fuel generally refers to a flexible fuel vehicle (FFV). It is a vehicle engine designed to run on multiple fuels. The most common thing is that it runs on E85 or gasoline. E85 is a form of gasoline blended with ethanol.

This ethanol is made from a variety of plants, such as corn. While most gasoline in the United States contains ethanol, the E85 formulation is made with a higher percentage.

While most people assume that E85 is always 85% ethanol, this is not the case. E85 is a blend of ethanol and gasoline composed of 51 to 85% ethanol. There are variations in the formula depending on the season and the location of the distributor. E85 sold during the winter months generally has lower levels of ethanol due to crops.

READ MORE: Ethanol (E85) vs Gasoline – Differences (Pros and Cons)

Can all cars use Flex Fuel?

The only cars capable of using E85 are those specifically designated as a flex fuel. These vehicles contain an internal combustion engine that can use conventional gas or an ethanol blend such as E85. The car will have a special badge indicating it is a “Flex-Fuel”, “E85” or “FFV”. Without this badge, you wouldn’t want to put E85 in the gas tank.

Another indication that your vehicle is flex fuel is if it has a yellow gas cap. There are also capless fuel fillers with a yellow ring around them, indicating that you could put E85 in the tank. These vehicles allow you to use any level of ethanol blend, even the conventional form. There are sensors in the flex fuel vehicle that determine what gas is being used so that adjustments can be made automatically. The sophisticated system determines exactly what fuel injection and timing are needed for complete combustion.

If you are still unsure, you can check your owner’s manual to see what fuel is needed. It should indicate what is best and what can be used. If all else fails, contact the dealer where you purchased your car or check online with the manufacturer.

READ MORE: Can regular gasoline be used in a flex-fuel vehicle?

Benefits of Flex Fuel E85

1. Cleaner burn

Many people worry about how gasoline affects the environment. Ethanol is cleaner for the environment. As a result, there are fewer toxic gases pumped into the atmosphere.

Flexible fuel helps minimize the amount of greenhouse gases. This eco-friendly variant will become increasingly popular in the coming years as we all try to do our part to make the world a cleaner place for everyone.

RELATED: The Pros and Cons of Ethanol Fuel

2. Sustainable production

Ethanol is produced by crops commonly grown in the United States. Most ethanol is made from corn, but it can also be created from sugar cane.

It is much better to buy crops that are grown at home than to buy oil from foreign countries. All that is needed to continue producing ethanol is more crops.

3. Flexibility

With the flex fuel vehicle, you have flexibility, hence the name. If you are at a gas station that offers E85, you can choose to fill the tank with it.

Otherwise, if the gas station doesn’t carry E85, you won’t run out of gas. Instead, fill with conventional fuel. The vehicle setup can adjust the timing and fuel injection to work.

4. Modern technology

The flexible fuel vehicle is built with the latest technologies, as evidenced by the installed electronic sensors. These high-tech advances allow the vehicle to quickly adapt to the fuel being used.

With the flex-fuel vehicle, you can use any blend of ethanol, from 10 to 85 percent. Your car will then determine how to adapt to that type of fuel for the best performance.

5. Tax exemptions

If you choose an electric vehicle, you benefit from attractive tax advantages. However, it’s not just an EV that offers tax breaks.

You can also enjoy a small tax savings with the flex fuel vehicle. Even a small reduction in your tax liability will be welcome.

6. Possible performance improvement

There are arguments both ways, so they must be considered. Some car enthusiasts swear that using alternative fuel can have a positive effect on performance.

There is no documented performance loss when filling the tank with E85. Due to advanced sensors and sophisticated technology, you may very well notice more horsepower and torque as a result.

Disadvantages of Flex Fuel E85

1. Dependence on cultures

We discuss how the flex fuel vehicle uses sustainable fuel, as it is created from corn or sugar crops. However, this production is not perfect. There are some problems with producing enough sugar and corn to meet demand.

Cultures are not used in just one way. Think of corn as an example. It is used for the production of food, feed, and ethanol. Therefore, not all corn production can be used to manufacture ethanol. Additionally, as more of it goes into ethanol production, the cost of food and feed will naturally increase as it becomes scarcer.

In addition, corn can fall victim to diseases that ruin crops. Additionally, bad weather can have a negative effect on the amount of crops produced. All this determines the availability of crops and their production cost.

2. Less reliable engines

Although the flex fuel engine is more advanced, there are some problems that make it less reliable. By using higher levels of ethanol, the engine will experience more wear.

Ethanol is known to absorb dirt. With this dirt inside the engine, there will be more corrosion and damage to the engine. For this reason, you can expect it to have a shorter lifespan than your traditional car engine.

3. Poor fuel economy

We previously mentioned the performance aspects of the flex-fuel vehicle. True, you could get more horsepower and torque, but at what cost? This extra power can reduce fuel economy.

The difference is not going to be extremely noticeable. Plus, with the cost difference between E85 and conventional gasoline, it should still be ahead.

4. Compatibility with gas stations

Flexible fuel has not yet reached all gas stations in the country. There are many regions and resorts that do not offer it at all. Unless you’re in the Midwest, you may never see a station with E85. However, this is expected to change in the coming years, but this upgrade requires significant investment in service stations and infrastructure.

Other ethanol quotas


Although this number may not seem familiar to you, it is the one commonly used. Most gasoline sold in this country contains some percentage of ethanol.

Most gas stations use a ratio of 10% ethanol and 90% gasoline. That’s what E10 is, and it’s used in over 95% of gas-powered vehicles on the road.


This mixture has been approved by the EPA. It contains 15% ethanol and 85% gasoline. You can use it on most light models from 2001 or later.

If you check with the manufacturers of these vehicles, almost all of them will approve the use of E15. You can get more specifications by reading your owner’s manual, but most 2021 and newer models often recommend using this wording.


You won’t find E25 as easily as others. This mixture contains 25% ethanol and 75% gasoline.

For now, E25 is only approved by certain manufacturers. For example, it can be used in some MINI and BMW models.


At the top of the spectrum is the E98 blend. This contains 98% ethanol and practically no gasoline.

Obviously, this mixture is not designed for road use in today’s cars. That said, some race cars choose it as a popular performance fuel.

MORE INFORMATION: What is diesel fuel gelation? (and how to prevent it)


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