E85 can be a practical, lower-cost fuel for some drivers, but it is not right for every car. The key question is compatibility: E85 is intended for vehicles designed to run on high-ethanol fuel, generally those labeled flex-fuel. In compatible cars, it can offer high octane and sometimes a lower price per gallon. It also delivers fewer miles per gallon than regular gasoline, so the pump price alone does not tell the whole story.
What Is E85 Gas?
E85 is a high-ethanol fuel blend sold in the United States. Despite its name, it does not always contain exactly 85% ethanol. Under U.S. fuel standards, the ethanol content can vary seasonally and by location; blends commonly range from 51% to 83% ethanol, with the remainder primarily gasoline. The blend can be adjusted to help vehicles start in cold weather.
Ethanol is an alcohol fuel most often made in the United States from corn. It contains oxygen and has a higher octane rating than typical regular gasoline, but it also contains less energy per gallon. That energy difference is the main reason a vehicle generally travels fewer miles on E85 than on gasoline.
E85 is different from E10, the gasoline blend containing up to 10% ethanol that is widely used in standard vehicles. It is also different from E15, which contains up to 15% ethanol and is approved for many, but not all, light-duty vehicles. Approval for E10 or E15 does not mean a car can use E85.
Is E85 Good for Your Car?
E85 can be good for a car if the manufacturer designed it to use E85 and the fuel makes financial sense for the driver. A flex-fuel vehicle (FFV) has fuel-system components and engine controls built to handle high-ethanol blends. Its computer adjusts engine operation based on the fuel’s ethanol content.
For a compatible vehicle, E85 may provide a high-octane option, and some drivers may find it costs less at the pump. However, lower fuel economy and local price differences can offset or exceed those advantages. For a vehicle that is not approved for E85, using it can cause drivability problems or damage fuel-system components. In that situation, the answer is clear: E85 is not good for the car because it is not an approved fuel.
How to Tell Whether a Car Can Use E85
The most reliable way to check compatibility is to consult the owner’s manual or the vehicle manufacturer. The fuel-door label may also identify the car as “FlexFuel,” “Flex Fuel,” or “E85.” Some FFVs have a yellow fuel cap or a badge on the rear of the vehicle, but these signs are not consistent across every make and model.
When checking a vehicle, the exact model year, engine, and trim matter. Two versions of the same model may use different fuel systems, and a vehicle’s appearance does not confirm that it is an FFV. A VIN lookup or a question to a dealer can help when the manual or label is missing.
- Look in the owner’s manual: Check the fuel requirements and any section on flexible-fuel operation.
- Inspect the fuel door: Look for an E85 or flex-fuel label, while keeping in mind that labels may be absent or hard to read.
- Confirm the exact vehicle: Use the VIN or contact the manufacturer if the information is unclear.
- Do not rely on aftermarket changes: A conversion kit or tuning modification does not automatically make a vehicle safe or legally approved for E85.
Benefits of E85 in a Compatible Vehicle
High Octane
E85 has high octane, which helps resist engine knock. Flex-fuel engines are calibrated to take advantage of the fuel within the limits of their design. Some vehicles may adjust timing or other engine settings when higher-ethanol fuel is detected. The actual power effect depends on the vehicle, its calibration, and operating conditions; E85 does not guarantee a noticeable performance increase in every FFV.
Potentially Lower Pump Price
E85 is often priced below regular gasoline per gallon, although prices vary widely by region, station, and season. That lower sticker price can be attractive, particularly for drivers who have convenient access to an E85 station. Yet a gallon of E85 generally moves a vehicle a shorter distance than a gallon of gasoline, so a lower price per gallon does not automatically mean lower cost per mile.
Domestic Fuel Supply and Emissions Considerations
Most U.S. ethanol is produced domestically, which contributes to the country’s transportation fuel supply. Its environmental effects are more complicated than a simple “cleaner fuel” label suggests. Lifecycle analyses account for factors such as crop production, fuel processing, transport, and land use. Results depend on the assumptions and methods used, so E85 should not be described as having zero emissions or as universally better for the environment.
Drawbacks of E85
Lower Fuel Economy
Because ethanol contains less energy per gallon than gasoline, vehicles typically get fewer miles per gallon on E85. The U.S. Department of Energy’s Alternative Fuels Data Center notes that FFVs typically experience a fuel-economy reduction of about 15% to 27% when operating on E85 compared with gasoline. The exact difference varies with the vehicle, fuel blend, driving style, weather, and route.
The change is easiest to notice in miles per gallon, but drivers may also notice more frequent refueling. A trip computer may calculate economy differently depending on the vehicle and fuel. For a fair comparison, drivers can track gallons used and miles traveled over several fill-ups.
Limited Availability
E85 is available at many U.S. stations, but access is uneven. It is easier to find in some states and regions than others, and a station may not carry it even if nearby locations do. A driver who depends on E85 may need to plan routes or use gasoline when E85 is unavailable. FFVs can generally run on gasoline as well as approved ethanol blends, but the owner’s manual remains the authority on permitted fuels.
Cold-Weather Effects
High-ethanol fuel can be more challenging to ignite in cold conditions. E85 sold in winter is blended to support cold-weather starting, and FFVs are engineered to operate on approved seasonal fuel. Even so, starting behavior and fuel economy can be affected by temperature. Drivers should use fuel sold for their region and season rather than storing or transporting an unsuitable blend.
Not Suitable for Non-Flex-Fuel Vehicles
Standard gasoline vehicles are not generally designed for E85’s ethanol concentration. Their fuel-system materials and engine controls may not tolerate the blend, and the car may run poorly or fail to start correctly. Use of an unapproved fuel can also affect warranty coverage if it causes damage. Drivers should not use E85 in a non-FFV just because the engine appears to run on it briefly.
Does E85 Save Money?
The best comparison is cost per mile, not price per gallon. A quick estimate can show whether E85’s lower price compensates for its lower fuel economy.
Cost per mile = price per gallon ÷ miles per gallon.
For example, if a vehicle gets 25 miles per gallon on gasoline at $3.50 per gallon, its fuel cost is 14 cents per mile. If the same vehicle gets 20 miles per gallon on E85, E85 would need to cost less than $2.80 per gallon to beat that gasoline cost per mile. This example is illustrative; actual fuel economy and local prices will differ.
For an approximate break-even calculation, divide the E85 miles-per-gallon figure by the gasoline miles-per-gallon figure. Multiply that result by the gasoline price. If E85 costs less than that break-even price, it may cost less per mile under those conditions.
In the example, 20 ÷ 25 = 0.80, and $3.50 × 0.80 = $2.80. If E85 costs more than $2.80, gasoline is cheaper per mile in this simplified comparison. Taxes, driving patterns, and variations in the actual ethanol blend can shift the result.
E85 Compared With Regular Gasoline
| Feature | E85 | Regular Gasoline |
|---|---|---|
| Typical ethanol content | About 51%–83%, depending on season and location | Often up to 10% ethanol in widely sold E10 |
| Vehicle compatibility | Designed for approved flex-fuel vehicles | Used by most gasoline vehicles that specify it |
| Energy per gallon | Lower | Higher than E85 |
| Fuel economy | Typically lower miles per gallon | Typically higher miles per gallon than E85 in the same FFV |
| Octane | High | Varies by grade; regular is commonly 87 AKI |
| Availability | Regional and less widespread | Widely available |
Octane ratings are commonly displayed in the United States as Anti-Knock Index (AKI), the average of Research Octane Number and Motor Octane Number. E85’s high octane does not mean it is appropriate for every high-performance or high-compression engine; the manufacturer’s fuel specification still determines what should be used.
What Happens If the Wrong Car Gets E85?
The outcome depends on the vehicle, how much E85 was added, and whether the engine was started. A non-flex-fuel vehicle may experience hard starting, rough running, a warning light, or stalling. A large amount of E85 may increase the risk of damage to fuel-system components not designed for high ethanol content.
If E85 is accidentally put into a non-FFV, the driver should avoid starting the engine and contact a qualified mechanic or roadside service for guidance. If the engine has already been started, the driver should stop in a safe place and seek professional advice rather than assuming the car will be fine. The mechanic can assess the amount added and the appropriate next step.
Drivers should also avoid mixing assumptions across fuel blends. A vehicle approved for E15 may still not be approved for E85. The vehicle’s fuel label and manual provide the correct limit.
Practical Tips for Using E85
- Verify compatibility first: Confirm the exact vehicle is a flex-fuel model before filling up.
- Compare cost per mile: Use real fuel-economy records and current local prices rather than comparing pump prices alone.
- Plan for station access: Check a reliable station locator or map before relying on E85 for a long trip.
- Use the correct seasonal fuel: Buy fuel from a reputable station and follow the vehicle maker’s guidance for cold-weather operation.
- Track results: Record miles and gallons across several tanks to account for changes in weather, traffic, and driving habits.
- Follow maintenance instructions: Use the maintenance schedule specified for the vehicle; do not assume E85 requires a universal extra service.
Frequently Asked Questions About E85
Can Any Car Run on E85?
No. E85 is intended for vehicles specifically designed and approved as flex-fuel vehicles. A standard gasoline car should not use it unless the manufacturer explicitly approves that fuel.
Does E85 Give More Horsepower?
Its high octane can support engine settings designed for ethanol, but a stock flex-fuel vehicle may not produce a noticeable power increase. Results depend on the engine and calibration. E85 should not be treated as a performance upgrade for a vehicle that is not approved for it.
Is E85 Cheaper Than Gasoline?
It may be cheaper per gallon, but it generally delivers fewer miles per gallon. Whether it is cheaper to use depends on the local prices and the vehicle’s fuel economy on each fuel. Cost per mile provides a more useful comparison.
Can a Flex-Fuel Vehicle Use Regular Gas?
Many FFVs are designed to use gasoline as well as approved ethanol blends, including E85. The exact permitted fuels are specified by the automaker. Drivers should check the owner’s manual rather than assume that every flex-fuel model has identical requirements.
Reliable Sources for E85 Guidance
For vehicle-specific fuel requirements, the owner’s manual and manufacturer information are the most important references. The U.S. Department of Energy’s Alternative Fuels Data Center ethanol fuel basics explains ethanol blends and fuel properties. Its E85 station locator can help drivers check local availability. The Environmental Protection Agency provides information on renewable fuel standards and fuel regulations.