Ethanol vs. No Ethanol in My Car

My car reliably gets 30, sometimes just barely 31, miles per gallon on the highway on long distance drives when running on “E10” gasoline.

When running on a tank of gasoline without any ethanol in it, during the same time of year over the same route, my car gets 34, sometimes just barely 35 MPG.

I do a lot of long-distance drives, and go to a few of the same places each year, so I can test this. Before recording MPG of non-ethanol gas, I fill up with it, and then use the tank up, and then fill it again and measure that tank.

“E10” ethanol gasoline gets somewhere between 86–88% the MGP of non-ethanol gas. As I’m running “E10”, with 10% of the fuel being ethanol, that meas that the ethanol is hurting my gas mileage more than if I just filled my tank up to only 90% full of gasoline. Instead of adding a few MPG to 90% of the gasoline, it is subtracting MPG from the gasoline in the mix.

Sadly, I don’t live in a state that forces individual gas grades to be labelled for ethanol content. The pumps just have one sticker on them, “May contain 10% ethanol” for all grades dispensed by the pump. My car requires premium grade fuel, so there is a trick. Premium fuel with 93 octane has ethanol, and 91 octane doesn’t.