Hate to break it to you, but in almost all cars, ethanol free does nothing for fuel economy. Unless you own a sports car or a turbo engine anything over 87 (or the equivalent wherever one lives) has absolutely no benefit for fuel economy. A manufacturer tunes a vehicle to a specific grade level, almost always your standard 87. Putting in premium grade will not make your engine run any different or any more efficient. Could it MAYBE make your engine last longer due to build up? I mean, maybe, but 99% of consumers probably don’t own their car to ever care. And even then, calculate how much more you are spending over 150k+ miles. You could probably buy two new engines for your car. Plush you are mistaken. Gas with ethanol added absolutely gives worse fuel economy. That is a fact, it contains less energy and you get less output from it. Don’t take my word for it, check for yourself. I believe you are confusing ethanol free with premium (much of which does happen to be ethanol free.) I’m not talking about buying premium grade I’m talking about buying ethanol free. Higher octane doesn’t equal more mileage that’s true. Octane refers to the fuel’s volatility, higher octane resists premature detonation under higher compression. Certain high compression engines need premium but none of mine do so I don’t waste my money on it. As for the economics you stated, nope. Ethanol free regular gas costs me about a dollar more, sometimes $1.50 more, for a 15 gallon top off and will get me a bit over 1 more mile per gallon. I still come out ahead.