[Porsche-O-Phile]

The R+M/2 method has been around at least since 1985, since it's mentioned in my 944 manual. Actually both systems are (it gives minimum octane requirements calculated by both methods).

If you want to run 106 octane gas in a newer car it won't hurt anything (except possibly the catylitic if it's leaded) but it won't really help anything either. Higher octane doesn't really do much other than ward off detonation due to very high c/rs, advanced timing or high boost levels.