Kurz Automotive Restyling
(301) 990-6314 7505 Rickenbacker Dr
If you don't mind waiting a bit...they do excellent job. DTMPower.net webmaster and others on there swear by it.
Kurz is in airpark. It really depends what you want to be done...something quick and dirty, you can pretty much ask your dealer where they take their cars to do bodywork. Something better...just need to ask around. But airpark area has many shops you can try, they are all about the same.
I'd ask around. The reason why is that dealers don't necessarily always go where the best work is done. It's a business, and they have body shops courting them.
I've seen plenty of high end imports at the shop Kai mentioned. Out of convenience I just took our 240 to Amatucci Bros. on rt 355 Frederick Rd in Gaithersburg. I just got the car back today (hood resprayed) and was impressed with the results. I'd recomend them.