L.A. Mechanic
If you are looking for basic work (oil changes, brakes, tune ups) I recommend Johann's Independent Mercedes on La Brea in Hollywood. I would not go there for issues unique to our cars which are better handled by La Jolla, Coupe King or Mark at Bavarian. As far as I have been able to determine he is one of the only remaining general mechanics in the central LA area who can work on an older car and not be intimidated or give you that look like they have no idea what a carburetor is. He has worked on all my cars over the last few years (1989 420 SEL; 2000 S430) and the 3.0 for some basic things that I don't do myself.
Good luck and keep us informed on any good leads you come across.