What kinda gas do you use?
 

Obviously this is a MB forum, so the OBVIOUS answer is 93 (and i guess 91 in states where they dont have 93%). My friend bought a 2003 S500 new a couple years ago and pours 91, which is the "medium" one in our state. The car runs great and power is great. I bought a CLK350 and i chose to use 91 as well. (i'm only asking because I had an award winning organic chemistry professor that worked for exxon a couple of years ago and he told me that there really is no difference, unless your car is really high performance) Does any one REALLY notice a difference while pouring good gas and "bad gas"?