Flex fuel, sold as E85, is cheaper per gallon than regular gasoline because ethanol costs less to produce than petroleum gasoline, and federal policy actively subsidizes its blending and sale. But the sticker price at the pump doesn’t tell the whole story. E85 contains less energy per gallon, so you burn through it faster, and the real savings depend on how much cheaper it is in your area.
Ethanol Is Cheaper to Produce Than Gasoline
E85 is a blend of ethanol and gasoline, typically containing somewhere between 51% and 83% ethanol depending on the season and region. Ethanol in the U.S. is made primarily from corn, and domestic corn production is enormous, keeping feedstock costs relatively low. The raw production cost of a gallon of ethanol consistently runs below the cost of refining a gallon of petroleum gasoline, which is subject to global crude oil prices, refinery capacity constraints, and geopolitical disruptions. Since E85 replaces a large share of that petroleum with cheaper ethanol, the wholesale cost drops.
Government Incentives Push the Price Down Further
Multiple layers of federal policy make E85 artificially cheaper than it would be on its own. The most direct mechanism starting in 2025 is the Clean Fuel Production Credit, which offers producers a tax credit of $0.20 per gallon for low-emission transportation fuels like ethanol. Facilities that meet federal wage and apprenticeship requirements can claim up to $1.00 per gallon. That’s a significant per-gallon subsidy that gets passed along through the supply chain.
Beyond direct tax credits, the Renewable Fuel Standard (RFS) requires fuel blenders to mix a set volume of renewable fuel into the national gasoline supply each year. For 2025, the total renewable fuel requirement sits at roughly 24 billion ethanol-equivalent gallons. To prove compliance, blenders use tradeable credits called Renewable Identification Numbers, or RINs. Every gallon of ethanol produced generates RINs, and blenders who exceed their mandated volumes can sell surplus RINs to those who fall short. This creates a financial incentive for retailers to sell more E85: the RIN revenue from each gallon of high-ethanol fuel effectively offsets a portion of the retail price, letting stations price E85 well below regular gasoline and still maintain their margins.
Lower Energy Content Is the Catch
Here’s the part many drivers overlook. A gallon of E85 contains substantially less energy than a gallon of regular gasoline (E10). Standard gasoline delivers roughly 112,000 to 116,000 BTUs per gallon. E85 ranges from about 84,000 to 95,500 BTUs per gallon, depending on the exact ethanol percentage in the blend. That’s a significant gap.
In practical terms, flex fuel vehicles running on E85 get roughly 15% to 27% fewer miles per gallon than when running on regular gasoline, according to EPA testing. The wide range reflects the fact that E85’s ethanol content varies. At the low end (51% ethanol, common in winter blends), you lose about 15% of your fuel economy. At the high end (83% ethanol, typical in summer), the loss approaches 27%. Either way, you’re filling up more often.
How to Tell If E85 Actually Saves You Money
The pump price of E85 needs to be significantly cheaper than regular gasoline before you come out ahead on a cost-per-mile basis. From a pure energy standpoint, ethanol contains about two-thirds the energy of petroleum gasoline. When you account for the typical ethanol content in E85 (averaging around 74%), the price of E85 needs to be at least 20.5% lower than the price of E10 gasoline to break even on energy value. That means if regular gas costs $3.50 a gallon, E85 needs to be at or below roughly $2.78 for you to spend the same amount per mile driven.
In corn belt states like Iowa, Minnesota, and Illinois, E85 often hits that threshold comfortably. Proximity to ethanol plants keeps distribution costs low, and state-level incentives sometimes stack on top of federal ones. In coastal states or areas far from ethanol production, the discount shrinks, and E85 may not actually save you anything once you factor in the extra fill-ups.
A Quick Way to Do the Math Yourself
Divide the price of E85 by the price of regular gasoline at your local station. If the result is 0.795 or lower (meaning E85 is priced at 79.5% or less of the gasoline price), you’re saving money per mile. If it’s higher than that, you’re paying more overall despite the lower sticker price. For example, if gasoline is $3.20 and E85 is $2.40, that ratio is 0.75, which falls below the breakeven line. You’d save money on E85. But if E85 were $2.70 at the same station, the ratio jumps to 0.84, and you’d actually spend more per mile on flex fuel.
This calculation assumes average E85 composition. In winter months when ethanol content drops closer to 51%, the energy penalty is smaller, and the breakeven threshold becomes more forgiving. In summer, when ethanol content climbs, you need a steeper discount to come out ahead.