States is all (r+m)/2, but for the life of me I can't remember the formula used in Europe. I've been running 94 Sunoco recently, because it's close to me. It's $.10 more expensive than 91, but it runs my A4 better than the 91 (which is typically what is termed "high Grade" around here). BP Amoco has 93, and I think their fuels are pretty good. I guess they do sell race gas at IRP here in indy, 110 or so. 94 is high enough to produce the kind of performance I want every day without putting me in the poor house.

 

Yeah most of our gas stations have 87,89,93, and some carry98,100.

t