|
You've pretty much got your answer, but I'll add that you will get the most power from a fuel with the lowest octane level that just barely prevents detonation. Additional octane, if not required to control detonation, will cost you power. I'm not certain if that translates directly to MPG numbers also, but I expect it might.
The only time a high octane fuel may give you more MPG, when not required to control detonation, is when it doesn't contain Ethanol like the lower grade. I've found about a 4% increase in mileage with my cycle when using 91 octane (87 is required) without Ethanol.
I don't think there is any definite answer to the exact penalty of 10% Ethanol - every car/cycle reacts differently.
|