quote:
Originally posted by wiswind:
Some of us are stuck with 10% ethanol in all gasoline at all stations due to EPA clean air mandates.
The Ethanol causes less polution, but contains less energy than gasoline, which translates into slightly lower MPG (all other things equal).
From what I have read, the higher octane does not have more energy (BTUs) but slower burning. The higher octane does enable more advanced timing, which can increase your MPG (or performance), IF your car's computer can make the adjustment for the higher octane.