[masraum]

I know that we all hate ethanol gas.

I'm pretty sure that I've got a handle on the fact if your motor requires 87 octane, then using higher octane not only doesn't help, but can actually hurt efficiency (higher octane burns more slowly)

So, if you had a vehicle that only requires 87 octane and won't do anything fancy/special if you put in higher octane, then (assuming comparable additives and quality) which gas is better to use, 87 octane with ethanol or 92 octane ethanol-free gas?

I put some of the ethanol free in the Subaru the other day and about halfway through remembered that the car only requires 87.

I'm not concerned with causing issues, I'm just curious theoretically, which would be a better/more efficient fuel to use.