And you usually lose less torque than power, so it won't matter much unless your engine is close to underpowered for the car or you're driving on a race track.
>Is there actually a fair bit of variance that is adjusted for in your vehicle?
The modern computerized fuel-injected ICE automatically adjusts for an incredibly wide variety of octane ratings and component percentages such as alcohol content.
Vintage carburetted engines could require careful mechanical adjustment if they were to be optimized for something other than the prevailing vintage gasoline when issued.
>operate differently when burning ethanol
Not in a very noticeable way when running. The problem is pure ethanol does not have enough vapor pressure to cold-start many engines, depending on how cold. Plus in case of fire during the daytime, the faint blue alcohol flame is virtually undetectable. These problems are overcome with the 15 percent gasoline content normally found in E85. Or with methanol, M85.
>you're certainly going to travel 30% fewer miles on a full tank
That's the big difference. Methanol has even less energy per gallon even though a gallon weighs about the same as a gallon of ethanol. About 5 percent heavier than a gallon of gasoline too.
>and you're likely going to have 30% less horsepower too.
This is not correct. The alcohol will burn with a much better antiknock rating than regular gasoline and if you step on it you can usually extract more horsepower from the same kind of engine, even if you do bring it up to a bit higher RPM, it's smooth as butter and roaring for more.
And you usually lose less torque than power, so it won't matter much unless your engine is close to underpowered for the car or you're driving on a race track.