Almost every gallon of regular gasoline sold in the US already has ethanol in it, and a few blends carry a lot more. The E numbers on the pump tell you how much. For a fuel seller, knowing what each blend is, and who can use it, is part of stocking the forecourt correctly.
Reading the E numbers
The number is the percentage of ethanol in the gasoline:
- E10 is up to 10% ethanol, the standard fuel at most pumps.
- E15 is roughly 10.5% to 15% ethanol.
- E85 (flex fuel) is 51% to 83% ethanol under the ASTM spec, varying by season and region; 85 is the marketing name, not the upper bound.
The rest of each blend is gasoline. E85's range shifts because colder months need lower ethanol for cold starts.
Who can use what
Essentially all gasoline vehicles can run E10, which is why it is the base product almost everywhere. E15 is approved for flex-fuel and most light-duty vehicles from model year 2001 and newer. E85 is only for flex-fuel vehicles built for high ethanol content. Matching the blend to the vehicle is the seller's responsibility to label clearly.
Why most gasoline is E10
E10 became the de facto standard for finished motor gasoline in the US, and nearly every engine is approved for it. When a customer buys regular unleaded, it is almost always E10, so for most fuel sellers E10 is the base product. This connects to the broader product and supply picture.
The fuel economy note
Ethanol carries about a third less energy than pure gasoline, so higher-ethanol blends give somewhat fewer miles per gallon. The effect is small for E10 and E15 and larger for E85. It is a clear factor for fleets weighing flex fuel. The same question comes up on the diesel side with renewable diesel and biodiesel.
The jobber side: RINs and blending
Ethanol is where the Renewable Fuel Standard touches a jobber's margin. Each gallon of ethanol carries a RIN, a Renewable Identification Number, and the party that blends the ethanol into gasoline separates that RIN and can sell it or bank it for compliance. Position decides who gets it. Buy pre-blended E10 at the rack and the rack seller keeps the RIN. Splash blend the ethanol yourself, into the truck or your own tank, and you are the blender who earns it. RIN values move with policy and the corn market, so run the math on current prices before building a blending position. Every blend you carry is also its own product with its own spec, cost, and tax, which is why FastDragon Fuel Jobber tracks each blend separately.
Common questions
Can E15 be sold year-round?
It depends on the state. Federal volatility rules historically blocked E15 from June 1 to September 15 in much of the country unless EPA issued an emergency waiver, which it did several recent summers. A 2024 EPA rule made E15 a year-round fuel in eight Midwest states (Illinois, Iowa, Minnesota, Missouri, Nebraska, Ohio, South Dakota, Wisconsin) starting in 2025. Check the current EPA fuel-waiver status for your state before committing a tank to it.
Does E15 damage engines or void warranties?
EPA approved E15 only for cars, light trucks, and SUVs from model year 2001 forward. It is not approved for motorcycles, boats, lawn equipment, or anything older, and running it there can void the warranty. The orange-and-black pump label exists to keep those gallons out of the wrong tanks.
How much worse is fuel economy on E85?
DOE fuel-economy data shows flex-fuel vehicles typically travel 15% to 27% fewer miles per gallon on E85 than on gasoline. E85 usually sells at a discount, so the cost per mile can still come out close to even. The per-gallon price alone overstates the savings.
What is the ethanol blend wall?
If nearly all gasoline is E10, ethanol can only make up about 10% of total gasoline demand. That ceiling is called the blend wall, and it is why ethanol producers push E15 and E85: those blends are the only way to move more ethanol gallons once every tank of regular already carries its 10%.
Is ethanol-free gasoline still available?
Yes. E0, often sold as recreation fuel, survives as a premium niche product for boats, small engines, classic cars, and other equipment that handles ethanol poorly. Stations that carry it usually price it well above regular, and for some rural and marina locations it is a steady traffic draw.