We had a terrible experience at Martens in our efforts to buy a new Passat, particularly with a salesman named Anthony Bradley. He was rude, condescending, and unprofessional to us from the start. He told us that our color choice was boring. He was openly hostile when we tried to negotiate on price with him. He lied to us when we talked to him, telling us that the car we were interested in had sold when (a) it remained on the dealer's website and (b) other dealers in the area could see it on the VW inventory system. He routinely told us that his price negotiations were only good if we would promise -- before beginning discussions on price -- that we were going to buy the car that day. Later, when I returned to the dealership, he was openly hostile and sarcastic, telling me that he would "have to look on the internet" for something that I had left at the dealership and which he had previously told me he had.
After we bought our car, I wrote a letter to the president of the dealership and the president of Volkswagen to complain. I got a call from VW apologizing. I got a letter from Harry Martens telling me that (a) my concerns were overblown, and the problems were really just one of "chemistry" and (b) there are always two sides to every story and he was sure that the sales staff would have a different side to the story. The response then went so far as to chastise me for sending the letter to Volkswagen and not just to the dealership.
In short, I cannot say this strongly enough: STAY AWAY FROM MARTENS. There are other dealerships in the DC area -- in College Park, Tysons, and Fairfax, that are all much more professional and more deserving of your business.