I have also found that German Auto Service on Dorsey Run Road in Jessup does very good work, but they are considerably more expensive than Chris and charge by the book instead of by the hour.
German Auto Service is a BIG nono. I originally went there because of the quick and cheap ($25 I think it was) oil changes. Then they started diagnosing work. It was all "needed" and having just bought my first E320 coupe I was like, alright, if you say so.
I liked the owners. A man and his wife. German.
There was one day-- shortly after they had just completed some work, $500 or so. I took it in because of one thing and the wife calls me frantically on the phone. And I am *not* kidding about the frantic part. "Your water pump is leaking BADLY!!!! We have to change it NOW!!!" I was actually physically tired while on the phone, and financially tired from the money *just* spent. Sounding exhausted and calm I just sighed "I can't do that right now, close it up and I'll come get it."
Got the car and everything seemed/felt a-ok. And remember at this point I knew absolutely NOTHING about this forum or specific W124 issues. On a whim, I thought up a way to get an un-biased second opinion.
Took it to Benchmark Motors in Columbia. Asked them to do an oil change. "Oh, by the way, can you look at the water pump to see how it is? Just look, nothing big."
Pick up the car and the folks say that the water pump is a-ok. To quote "bone dry". I told them why I asked and told them German Auto Service told me it was "leaking badly". Again, the tech says "bone dry". That was the day I stuck with Benchmark, 7 years ago.
They haven't always been perfect (I think Stuart broke my light once and tried to fix it with some weird putty, he never confessed to it, but when you're in the car 6,7,8 hours a day you get to know it like the back of your hand) but they have always been honest with me. They even helped me above and beyond on several occasions, one time with Maryland's crazy emissions requirements.
I appreciate them and can highly recommend them.