Its possible that you saw an S55, non supercharged. There is no s55 "Kompressor". The owner probably put the badge on himself, ever think about that? Your M3 probably could have given him a run. Merceded does have TENTATIVE plans to supercharge their AMG line, but so far the AMG C32 is the only model with a supercharger, and no there is no extra "Kompressor" badge on it. You really should think about these things before jumping to such conclusions. People debadge and add extra B.S. badges all the time to make their car look like something it isn't, especially in Europe.