An extremely unscientific analysis of ethanol vs. pure gasoline

by wfgodbold

And by unscientific, I mean I have two data points. One is the control, and the other is, well, not the control.

I’m not going to let a little detail like that deter me from making grand generalizations, though! What kind of internet arguer would I be if I let facts get in the way of a good rant?

When I last filled up my car, I used pure gas (meaning without ethanol additives); at the time, the cost per gallon of pure gas was $3.479 and the cost per gallon of ethanol-added gas was $3.379. The price when I filled up yesterday was $3.629 per gallon of pure gas and $3.599 per gallon of ethanol-tainted gas.

On the first tank (of standard, ethanol-laced gas), I drove 505 miles on 11.682 gallons of gas, got 43.1 mpg, and spent 7.83¢ per mile traveled (at today’s price, it would have been 8.34¢ per mile).

On the second tank (which was pure gas, without ethanol), I drove 496 miles on 10.540 gallons of gas, got 47.1 mpg, and spend 7.71¢ per mile traveled (at the price when I first filled up, it would have been 7.39¢ per mile).

Needless to say, I won’t be filling up with ethanol-infused gasoline if I can help it (and thanks to pure-gas.org, it’s easy to find stations with pure gas).

I saved a gallon of gas, saved money, and went the same distance; ethanol made my car ~9% less efficient, and is only ~3% (or less) cheaper than pure gas.

If I remember right, current ethanol gas is ~10% ethanol. If you took that 10% ethanol out of the 11.6 gallons I used to go 505 miles, you’d have ~10.5 gallons of gas, which is what I used to go 496 miles.

Why do we add ethanol to our gas, again?

*Disclaimer: I drive an ’06 Prius. In my defense, I got it at a substantial discount (very substantial (by which I mean it was a hand-me-down)).

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