Is E15 Ethanol Bad for Your New Car’s Engine? Let’s Review the Facts

Updated on January 21, 2019
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My passion for automobiles and engines started as a hobby and has since become my work.

If you drive a car, truck, or SUV, chances are that it runs on fuel that has ethanol in it. Ethanol as a fuel has been around as long as the automobile. As we move into the automotive future of higher fuel efficiency and lower emissions, increasing the use of ethanol is an important way to get us there.

There have been concerns voiced about the use of higher concentrations of ethanol in our gasoline supply. Is ethanol bad for your engine? Let’s take a rational look at ethanol and what it can do for us as we move forward toward that future.

Ethanol Has a Long and Interesting History

Ethanol is one of the earliest products ever made by man using a biochemical process. It is also known as alcohol, ethyl alcohol, and drinking alcohol.

The fermentation of sugar since ancient times has produced ethanol, the intoxicating psychoactive substance present in alcoholic beverages. The production of ethanol goes as far back as the Neolithic era, approximately 9,000 years ago. Discovered in China, this earliest discovered fermented alcoholic beverage was made of wild grapes, hawthorn, rice, and honey.

Fermentation has its limits in terms of ethanol/alcohol content produced. This is because most yeasts are unable to reproduce in an environment that has a higher than 15 percent ethanol content. The solution to this “problem” was discovered in the first century A.D. Greek alchemists were the first to distill fermented solutions and create higher proof beverages.

Synthetic ethanol was first prepared in 1825 by Michael Faraday. His discovery used a similar process to that currently used to industrially synthesize ethanol. Today, fermentation and ethylene hydration (a petrochemical process) are the two most common ways of creating ethanol.

Ethanol has a long history as a fuel for heating and lighting. Ethanol was used as lamp fuel in the United States since 1840. Ethanol has also been widely used as a solvent for flavoring, coloring and medicinal products. You will find ethanol in personal care products such as perfumes, deodorants, and mouthwashes. It is a primary ingredient in hand sanitizers and medical wipes.

Over 100 Years as an Auto Fuel

More recently, ethanol has been used as a fuel for internal combustion engines. Its use as an automobile fuel goes back to 1896 when Henry Ford’s first car was designed to run on pure ethanol. Ford’s Model T, introduced in 1908, was one of the earliest flex-fuel vehicles, able to run on either gasoline or ethanol!

During the 1920s, Standard Oil started to add ethanol to gasoline to reduce engine knocking and increase octane. In the 1940s, the US Army built the first American fuel ethanol plant, which supplied fuel to the Army. Due to the extremely low price of gasoline from the 1940s through the 1970s, ethanol was not used in publicly available vehicle fuel. The oil embargoes and gasoline price hikes of the 1970s renewed interest in ethanol as an energy source for cars and trucks.

Ethanol Becomes Part of the Pollution Solution

Starting in the 1980s, oxygenates such as MTBE and ethanol were mandated in gasoline to reduce emissions. MTBE was ultimately banned due to the risk of groundwater contamination, leaving ethanol as the only remaining option.

Ethanol Helps Reduce Our Dependence on Foreign Oil

In 2005, the EPA’s Energy Policy Act of 2005 mandated that gasoline sold in the US had to contain a certain minimum amount of renewable fuel such as ethanol. In 2006, the Renewable Fuel Standard Program (RFS) encouraged the blending of ethanol into gasoline used for vehicle fuel. This was followed by 2007’s Energy Independence and Security Act, requiring 15 billion gallons of renewable ethanol fuel by 2015. This led to a huge boom in corn ethanol production.

Today, over 95% of all gasoline for automotive use contains ethanol. The average gallon of gasoline coming out of a gas pump in the US contains 90 percent gasoline and 10 percent ethanol. This blend is known as E10 and it is safe for use in 2001 or newer cars, trucks, and SUVs.

Reaching the Limits Of E10

Ongoing developments in technology and the urgent search for greater fuel efficiency in new vehicles are pointing to the need for a higher concentration of ethanol in our gasoline supply. In addition to the E10 blend that we use on a daily basis, there is a need to add an E15 blend to our choices at the pump. E15 contains 85 percent gasoline and 15 percent ethanol.

How E15 Helps Improve Emissions and Fuel Efficiency

Automakers are being pressured on two different fronts. They are not only required to meet higher and higher fuel economy standards, but also must meet tightening emissions standards for greenhouse gas emissions.

One easy way to do this is to make engines smaller. A smaller engine gets better mileage and puts out fewer emissions. But smaller engines generally put out less power, which is not a desirable feature for most drivers today.

To solve this problem, vehicle manufacturers are adding turbochargers and higher compression ratios to these smaller engines. This restores the performance level to one that will satisfy today’s buyers. So far, these engines have been designed to run on E10. But these engines will need a different fuel blend to get to the next level of performance, economy, and low emissions. This is where E15 comes in.

E15 Means More Power With Fewer Emissions and Better Economy

The higher percentage of ethanol in E15 provides a significant advantage in getting more power out of these smaller engines. Just as it was originally used in the 1920s as an octane enhancer and knock reducer, the higher ethanol content of E15 is the key to producing the higher-octane fuels that these next-generation engines will require.

The higher compression ratios that will be used in these new, more powerful engines must have improved fuel with more octane to operate efficiently and safely. E15 is the solution to meeting these new standards for both fuel-efficiency and greenhouse gas emissions. Pure ethanol has a very high octane rating of 113. It is the most cost-effective source for boosting octane and knock resistance. Period. It is also the cleanest and the safest.

Most New Vehicles Are Approved to Use E15

As the manufacturers of cars and trucks prepare for a future that includes E15 as the preferred fuel for their new more efficient vehicles, they have been testing and approving the use of this next-generation fuel in their current vehicles.

E15 Has Long-Term Benefits

Because E15 contains more ethanol and therefore less gasoline than E10, one immediate benefit is to reduce our dependence on oil for vehicle fuel. This alone could reduce gasoline consumption by as much as 4.4 percent by 2040, according to a recent MIT study. It could also reduce CO2 emissions by up to 35 metric tons per year. That’s a win-win!

Is E15 Safe for Your Car, Truck, or SUV?

If your vehicle appears in the list above, you should have no problem using E15. During the last three years, E15 has established itself as an economical, safe, and popular vehicle fuel, with E15-fueled vehicles covering almost 200 million miles. There has not been a single verifiable case of poor performance or engine damage reported during that time, proving that ethanol is not bad for your engine. An extra bonus is that even though E15 has higher octane than E10, it normally costs you less per gallon.

Where to Find E15

The availability of E15 has been ramping up slowly. Because there are not yet any vehicles on the roads that are required to use E15, the appearance of E15 pumps at gas stations is proceeding at a measured pace. The government does have programs in place that encourage fuel retailers to install E15 pumps, and that is helping to increase the availability of E15.

Once that the new-generation vehicles that must have E15 are announced and start rolling off the production lines, we will see E15 pumps appearing quickly across the country. In the meantime, you can check on the availability of E15 in your area here.

Beyond E15: Higher Octane Ethanol Fuels Are in Our Future

As exciting as these new developments in vehicle fuel-efficiency are, this may just be the beginning. Once we successfully transition to the next generation of cars, trucks, and SUVs powered by E15, the challenge to achieve even greater results will still face us. Future fuels with blends of 20 percent, 30 percent, and even 40 percent ethanol may become commonplace. As we enter that brave new world of previously unimagined fuel economy and reduced emissions, we will look back upon these early days when E15 became commonplace. This will be where it all started, where the path to a brighter, cleaner, high-octane future, using the full potential of ethanol, truly began. Not only is ethanol not bad for your engine, but it is also the key to a less oil-dependent world that has cleaner air for us all to breathe.

Will you be a part of the transition to an ethanol future? Join the move to E15. You can use it today, and you can count on it tomorrow.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2017 Daily Driver


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    • profile image

      Rusty Shackleford 

      10 months ago

      Eff ethanol.

      E0 all the way.

    • profile image


      15 months ago

      Many people compare E-15 (Unleaded 88) to regular 87 octane. Some of us are quietly using Unleaded 88 instead of midgrade 89. It saves a bundle of money -- many stations over-price midgrade -- and the difference in fuel economy is miniscule compared to saving anywhere from 25 cents to 70 cents per gallon.

    • profile image

      J in Colorado 

      15 months ago

      This article is a total whitewash supported by the big corn ag companies. Ethanol has less energy than an equivalent volume of gasoline. The higher the ethanol content the lower your mileage. Automakers are generally against higher ethanol content in gasoline. We export gasoline now. This is politics driven by powerful mid continent ag interests.

    • profile image

      Where is that list 

      19 months ago

      Where is the list of approved vehicles?

    • profile image

      wanna see list 

      21 months ago

      I can't find the List either. I agree with HoftHome.

    • profile image


      21 months ago

      "If your vehicle appears in the list above..."

      I apparently missed something: where exactly is this list (of E15-safe vehicles)?

    • profile image

      Terry B 

      22 months ago

      Filled up today with e15 by mistake , not a fan of it how much trouble did I do to my car . I have no plans on using it again (2016 Hyndia Sonata


    • profile image


      2 years ago

      Small turbo cars (like the Chevy Cruze), with 1.4-1.8 liter turbo cars, often perform horribly on regular gasoline (87 oct) in hot summers.

      One solution is to switch over to E15. It allows the engine to run cooler, has higher low RPM torque, and allows for higher turbo boost values.

    • profile image

      thomas m welch 

      2 years ago

      isn't e anything bad for classic cars and lawn equipment?

    • profile image

      Richard Mertens 

      2 years ago

      Gallon for gallon, ethanol has 1/3 less the fuel mileage than gasoline. It is more expensive per gallon as well, compounding the economic problem of fuel costs. It takes 1.0 BTU to produce 1.1 BTU from ethanol, a horrible rate of return on energy investment and to say nothing of the problem of putting marginal land under the plow to supply corn for ethanol.


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