Cheaper per gallon. Not automatically cheaper per mile.
E85 is always cheaper at the pump, and you always burn more of it. That makes this one subtraction: the price gap has to beat the 26.3% economy penalty measured across 1,538 factory flex-fuel vehicles, or you lose money.
In 95 quarters of DOE data going back to 2000, the national average has cleared that bar 0 times — best ever 21.6%. This is a local question or it is nothing. The West Coast clears it today at 39%, and the corn belt does not, at 17% — not because Midwest E85 is expensive, but because Midwest petrol is cheap.
Real octane. Whether it does anything depends on your engine.
Octane only buys power where the engine was already pulling timing to avoid knock — under boost, under load, when it is hot. Knock control can hand back timing it was taking away; it cannot invent advance beyond the factory map. So the answer is entirely about which car you own.
Oak Ridge measured a stock turbocharged direct-injection car 5% quicker on nothing stronger than E15. On naturally-aspirated cars with no tune, independent dyno testing returned −1.5%, −0.2% and +2.4% — noise. And E85 is not 105 octane: the ethanol industry’s own trade association says that figure is wrong. Our eligibility check tells you which category your car is in before you spend anything.
A genuine carbon case, and a genuine scientific fight about it.
The US government’s own lifecycle model puts corn ethanol at 48.8 gCO₂e/MJ against gasoline’s 93.1 — about 1.5 tonnes of CO₂e a year if you drive 12,000 miles at 24 mpg. A 2022 PNAS paper measuring actual cropland expansion instead of modelling it concluded ethanol is at least 24% worse than gasoline, which turns that saving into a loss. USDA disputes the soil-carbon maths. Neither has been retracted.
Three US government bodies price land-use change at 4.99, 19.8 and 26.3 gCO₂e/MJ — a five-fold disagreement about the same fuel. At the tailpipe E85 cuts benzene by up to 84% and raises acetaldehyde and formaldehyde two to twenty times. We are not going to resolve this on a landing page. We are going to show you both ends of it.
The BTEX group, benzene included. This is the most robust air-quality argument for ethanol and it is a real one.
Consistent across test programmes, though the underlying vehicle data is Tier 1 and Tier 2 era rather than current.
Real at high ethanol blends in GDI engines, where particulate emissions are otherwise a known weakness. Below about E20 the effect disappears into test variability.
The honest counterweight. Acetaldehyde is reasonably anticipated to be a human carcinogen and both are ozone precursors. Worse in the cold. E85 does not simply burn cleaner — it trades one set of toxics for another.
We will talk you out of this if the numbers don’t work.
E85 is cheaper per gallon, but you burn about a quarter more of it. At national average prices right now, converting actually loses money — and on DOE’s own numbers the national average has never once cleared break-even in 95 quarters going back to 2000. The best reading ever recorded was 21.6% against the roughly 26% required.
It pays only where the local spread is unusually wide, and the intuition about where that is turns out to be backwards. The break-even test is a percentage, so what decides it is how expensive your gasoline is — not how cheap the E85 is. The Midwest sells the cheapest E85 in the country and still fails the test, because Midwest gasoline is cheap too. The West Coast sells the most expensive E85 in the country and clears it, on California gasoline at $5.69.
The calculator tells you the truth about your own postcode. We’d rather lose the sale than sell you a loss.
E85 $3.49 · gasoline $5.69
Clears break-even
E85 $3.14 · gasoline $3.88
Below break-even
E85 $3.18 · gasoline $3.92
Below break-even
E85 $3.09 · gasoline $3.72
Below break-even
E85 $3.38 · gasoline $3.74
Below break-even
E85 $3.58 · gasoline $3.95
Below break-even
AFDC Alternative Fuel Price Report, April 2026. Break-even needs a spread above the 26.3% economy penalty — which is why the West Coast at 38.7% works and the corn belt at 16.9% does not.
Now check your own car.
Thirty seconds, no account, and it will tell you if the answer is no.