I've already received a few responses questioning whether the 95 octane recommended by Audi can be compared to the octane ratings of U.S. fuel. Audi says 95 RON (or 91 AKI). I assume that RON is the same as the (R + M)/2 method used by U.S. gasoline suppliers. Perhaps I'm mistaken, and (R + M)/2 is the same as AKI?