The first thing people ask
You can still run regular gasoline. Any pump, any time.
A conversion doesn’t replace one fuel with another. It makes the car flex-fuel — E85 when it pays, ordinary gasoline when it doesn’t, and no consequence for mixing them in the same tank.
Any pump, any tank
Regular, premium, E85, or half a tank of one on top of the other. Nothing to switch and no mode to select.
The sensor does the work
It reads the ethanol content of whatever you actually put in, and the controller trims fuelling to match — continuously, not once at install.
Which is the whole point
‘E85’ is 51–83% ethanol depending on the season and the state. A car that couldn’t cope with a range couldn’t run E85 in the first place.
Why anyone does this
Three reasons to convert. Each one has a catch.
Cheaper per gallon. Not automatically cheaper per mile.
The price gap has to beat the economy penalty. On national averages it never has — this is a local question or it is nothing.
Real octane. Whether it does anything depends on your engine.
Octane only buys power where the engine was already pulling timing to avoid knock. Which means boost, and which means it depends on your car.
A genuine carbon case, and a genuine scientific fight about it.
Argonne’s lifecycle model and a 2022 PNAS paper reach opposite signs on the same fuel. Neither has been retracted.
Before you spend anything
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. On DOE’s own numbers the national average has never once cleared break-even in 95 quarters. It pays in some postcodes and loses money in most — so check yours.
Why it pays on the West Coast and not the corn beltEligibility
Can your car run E85?
We decode your VIN against NHTSA’s database — or pick the car from EPA’s catalogue if you don’t have it to hand — then run it through the same checks a mechanic would make in your driveway.
We convert vehicles 6 model years and older. Anything newer is likely still under a powertrain warranty, and a fuel conversion is the modification a manufacturer can most plausibly blame for an engine failure — we’d rather you kept the warranty.
Booking coverage is narrow. EPA has listed an E85 conversion system for particular Ford, Chrysler, Mercury and Toyota models of 2006, 2007 and 2010, and nothing else. We'll decode and price any vehicle, but where no listing covers yours we'll say so rather than book it.
Enter a VIN and we’ll tell you what your car is, whether it can be converted, and what it would cost.
How it works
Four steps, one visit, no workshop.
Check the car
VIN in, answer out. Thirty seconds, no account.
Check the maths
Your local pump prices against EPA’s measured economy for your car.
A mechanic comes to you
Certified, at your address, about an hour.
Commissioned, not guessed
Sensor verified, fuel trims watched, road-tested under load.
Is there even E85 near you?
Worth answering before anything else. There are about 4,200 public E85 stations in 44 states, and they are not evenly spread — if your nearest is a forty-minute round trip, the spread stops mattering.
Does it actually pay?
Cost savings
Defaults are the national averages. Change the two pump prices to what you actually see near you — that’s what decides this.
E85 needs to be at least 26% cheaper than your gasoline to break even, because you'll burn 26% more of it. At your prices it's only 19% cheaper — so converting would cost you about $171 a year in fuel. E85 would have to drop to $3.01/gal before this makes financial sense. We'd rather tell you that than take your money.
E85 would need to fall another $0.30/gal before converting makes financial sense at these prices.
The US government’s current lifecycle model. Tonnes of CO₂e you would avoid each year.
Counting cropland expansion as observed rather than modelled. Tonnes you would add.
Same fuel, same mileage, opposite conclusions — the entire gap is one contested question, how much land-use change is charged to corn — Argonne GREET 2024 4.99, California (CARB) 19.8, EPA (RFS2, 2010) 26.3, Lark et al. (observed) 29.7 gCO₂e/MJ. USDA has published a detailed rebuttal of the Lark figure; Lark’s team has published one of the model Argonne relies on. Neither has been retracted, so we show you both and let you weigh them.
DOE reaches the same conclusion by a different route. Rather than compare prices per gallon, the Alternative Fuels Data Center converts E85 to a gasoline-gallon equivalent and publishes that directly: $4.30 per GGE against $4.09 for gasoline. On the government’s own arithmetic, national-average E85 costs $0.21 more per unit of energy than the petrol it replaces. We think our figure above is the more useful one because it uses your prices — but if you would rather not take our word for the penalty at all, take theirs.
Where the 26.3% penalty comes from — and why it is a range. We took every factory flex-fuel vehicle in EPA’s certification dataset that carries both a gasoline and an E85 rating — 1,538 of them — and measured the difference. Kit vendors typically advertise 15–25%. The measured number is worse, and we plan against the measured one.
But 26.3% is the median of a distribution, not a fact about your car. The middle half of those vehicles fell between 24.1% and 28.6%, and the outer ends ran from 21.4% to 32.1% — enough spread to move a marginal case either side of break-even on its own. If you ran the eligibility check above and your car carries its own EPA E85 rating, we use that measured figure instead of this average, which is always the better answer.
The science
Most of what you've read about ethanol is wrong.
“E85 makes rubber swell the most”
Backwards — swelling peaks near E17 and returns to baseline at E85.
“Ethanol corrodes all fuel-system metals”
Under 10 µm/year on nearly every metal. The damage is galvanic.
“You’ll lose 15% fuel economy”
26.3%, measured across 1,538 factory flex-fuel vehicles.
“E85 is 105 octane”
94–96 AKI. The ethanol industry’s own trade body says 105 is wrong.
“A conversion kit adds 5–20% power, no tuning needed”
About 1% without boost. Octane pays where the ECU was pulling timing.
“A converted car starts in the cold just like a factory flex-fuel one”
It doesn’t. Yours has no high-ethanol cranking map; an FFV does.
Every figure in this product is keyed to a published source.
See all of them
For mechanics
$150 a job. An hour, once you’ve done three.
Certify first: 63 minutes of ORNL and EPA material, then an exam written to fail anyone who only read forums.