I know I'm digging up an old thread here, buttt... this is very useful info. As an automotive noob, I've always had this misconception that high octane fuel was too expensive to bother with, and only really used by people who are a bit precious about their car/s. But judging by this info and the fuel prices where I live, 98 octane is actually the most economical at about 14c/km and regular ULP least economical at 18c/km. Saving money and saving my car by using better fuel - awesome :)