San Diego area service.
 

Here are two that I found.

Rudi's ******** Stuttgart
7961 Balboa Ave
San Diego, CA 92111
858-560-5068

Auto Tech Service Center
910 El Cajon Blvd
El Cajon, CA

Excellent SD Area Diesel Mercedes Mechanic
 

Daniel Morgan's Automotive
637 Valley Ave, Solana Beach, CA
(858) 259-1291

http://maps.google.com/maps?f=q&hl=en&q=morgan%27s+automotive+solana+beach,+ca&ie=UTF8&om=1&z=15

Great shop run by two honest mechanics. They only fix what needs to be fixed and do it right the first time. I have owned my car for two+ years, but it has been serviced here (by previous owner) for around 20.

i used to work for rudi's i can vouch for the 100%. they have all the latest factory diagnostic tools.

The best shop I've found...
 

DIETER FISCHER'S MERCEDES SVC
8699 LA MESA BLVD
LA MESA
91941-3903
(619) 460-1498

I posted a detailed message regarding my experiences with Dieter's shop vs the general perception others have in the thread titled "San Diego, CA".