After picking up the bimmer in Munich, I preceeded to drive it 2900 miles and the highest octane sold (that I could find) was 83 or 85... once in a while I could find 87, but that was it... The car still ran like a raped ape, went 135 mph, and gave me an awesome 12.6 mpg for the tank-full. Now, in the Azores I'm treated to 89 and car performs as well... maybe pulls a little harder through the powerband , but I attribute that to the engine still breaking in, not raising the octane 2 points. Also, the gas mileage is up to 15.2. I am a lucky guy. (Don't flame my engine break-in therory, I believe the motor continues breaking in until the 8-10,000 mile mark)
Krafty