E0 vs E10 vs E15: Ethanol Blends Compared
The difference between E0, E10, and E15 is simply how much ethanol is in the gasoline: 0%, up to 10%, or up to 15%. That single number drives everything else: energy content, octane, price, storage life, and which engines can legally use the fuel. This guide puts all three blends side by side so you can pick the right one in seconds.
The Full Comparison Table
| E0 (ethanol-free) | E10 (regular) | E15 (Unleaded 88) | |
|---|---|---|---|
| Ethanol content | 0% | Up to 10% | Up to 15% |
| Typical octane | 87 to 91 (REC-90 is 90) | 87 | 88 |
| Energy per gallon (approx.) | ~114,000 BTU | ~110,200 BTU (about 3% less) | ~108,300 BTU (about 5% less) |
| Approved vehicles | All gasoline engines | All gasoline vehicles | 2001+ cars and light trucks, all FFVs |
| Motorcycles, boats, mowers | Yes, ideal | Yes | No, federal prohibition |
| Price vs regular | Often 50 cents to $1+ more | Baseline | Usually 10 to 30 cents less |
| Storage life | Up to about 6 months | About 3 months | About 3 months |
| Availability | Select stations, marinas | Everywhere | ~4,600 stations, Midwest-heavy |
Energy figures are approximate, based on DOE Alternative Fuels Data Center values for gasoline (about 114,000 BTU per gallon) and ethanol (about 76,100 BTU per gallon). Your real-world mileage will vary with the vehicle, the season, and the exact blend at the pump.
What the Numbers Mean in Practice
Energy and mileage. Ethanol holds about a third less energy than gasoline, so each step up in ethanol costs a little mileage. E10 gives up roughly 3% of E0’s fuel economy; E15 gives up roughly 1 to 2% more than E10. Most drivers cannot feel differences this small.
Octane. Ethanol is a cheap octane booster, which is why the blends climb slightly: 87 for E10, 88 for E15. The extra point helps knock-sensitive turbo engines a touch, but it is not a performance upgrade you will feel in normal driving.
Price. E15 is usually the cheapest of the three because ethanol costs less than gasoline. E0 is the most expensive because it has no cheap ethanol in it and sells in smaller volumes. E10 sits in the middle as the baseline.
Which Blend for Which Engine
Daily-driven car, any age: E10. It is everywhere, it is priced fairly, and your car was certified on it. If your car is 2001 or newer and a station near you sells E15, that is usually the better buy: cheaper per gallon with a mileage loss too small to matter. Compare them directly in our E15 guide.
Motorcycle, boat, or small engine: E0 if you can get it. These engines and their fuel systems were often not designed for ethanol, and they sit unused long enough for water absorption and phase separation to cause real damage. E10 is acceptable if you use the fuel up quickly and add stabilizer for storage. E15 is federally prohibited in all of them. Find no-ethanol fuel on our ethanol-free gas station guide.
Flex-fuel vehicle: any of these, plus E85. An FFV can drink the whole spectrum. For the economics of going all the way to E85, see our E85 guide.
Classic or collector car: E0. Older fuel systems with original rubber parts and carburetors are the most vulnerable to ethanol, and classics spend months parked. REC-90 at 90 octane is a popular choice.
The Storage Rule of Thumb
If an engine will sit for more than a month or two without running, ethanol content becomes the most important property of the fuel. E10 and E15 start to risk phase separation after a few months in a vented tank; E0 stored properly in a sealed container lasts roughly twice as long. For winterizing a boat or mower, fill it with ethanol-free fuel plus a stabilizer, or run the carburetor dry. It is the cheapest insurance in this entire article.
Common Confusions, Cleared Up
Unleaded 88 is E15, not a different fuel. The “88” is the octane rating. It confuses everyone at first; you are not alone.
Premium is not on this chart. Premium describes octane (91 to 93), not ethanol content, and premium at most stations is still E10. You can buy premium E10, and in rare cases ethanol-free premium, but “premium” and “ethanol-free” answer different questions.
Higher ethanol is not higher quality. The blends are not good, better, best. They are different tools: E15 for cheap miles in modern cars, E10 as the universal default, E0 for engines that need pure gasoline.
FAQs
Can I switch between E0, E10, and E15 freely?
If your vehicle is approved for all three, yes. Mixing them in the tank just produces an in-between blend, and the engine will not notice. The only hard rule is never putting E15 in an engine that is prohibited from using it.
Which blend gives the best gas mileage?
E0, because it has the most energy per gallon. But it costs more per gallon too, so best mileage does not mean lowest cost per mile. E15 usually wins on cost per mile for eligible cars.
Is E15 safe for a 2005 car?
Yes, federally: the EPA approved E15 for 2001 and newer light-duty vehicles. Still check your owner’s manual, because some automakers limit certain engines to E10, and the manual controls your warranty.
Why can’t motorcycles use E15?
Federal law prohibits it. The EPA’s E15 waivers excluded motorcycles, boats, and small engines over concerns about heat, materials compatibility, and misfueling. E10 remains the maximum legal ethanol blend for them.
Facts verified October 2026. Station counts and prices vary by state and change over time.