My recommendation is FunKtion Auto in Dulles, VA. www.funktionauto.com.

They do all kinds of work on all cars, but most of their business is BMWs, any model any year. What makes them a good shop is that their techs are very meticulous and thorough. They will explain to you exactly what work needs to be done, and why, they'll let you know what the car needs now, and what it will need down the road so to speak, and let you decide.

They also do not get paid on commission as most shops do. This means they take the time to clean the grime and sludge out of the undercarriage before getting to work, and after they are done. They'll check the car to make sure all clamps, fitting, etc are tight, clean, free of rust/corrosion/grime/etc. They have a tendancy to treat customers cars like their own. They like to build relationships with customers, so that they know the history of the car and the habits of the driver.