My 2008 535i had a problem with the fuel injector (seems like a common problem for the *35 engines). I took it to Classic BMW to get it fixed. They replaced the injector, but the service while I was there was horrible. First, they have a rental car facility on-site, and that means that you'll take your nice BMW to the dealership, only to drive away with a Pontiac or Cobalt from Enterprise Car Rental. They kept on telling me that they'd need to keep my car overnight, but I didn't want to get stuck driving an awful (I really mean horrendous) Pontiac for 2 days! So I managed to get them to expedite the service. Anyway, of course, a 3rd party rental car means a lot more paperwork. You actually have to stand in line, fill out rental car forms, give them your credit card, get hassled about getting insurance, etc. The worst part is the agreement that the rental car company has with the dealership doesn't allow you to drive a decent car! You'll get the worst cars out there. If you want a better car, you'll have to pay for the rental out of your own pocket! So when they advertise "loaner cars", beware of what you're getting into.
Upon delivery of my BMW, I saw horrible water streaks all over my car because they had washed it, and I don't know what kind of carwash they have. The car looked dirtier than when I had dropped it off. Also, the guy didn't use a paper floormat when he got in and my carpet being beige, there were spots all over it. And get this: my upholstery is beige and there was a nice big hand print on the inside door handle! Anyway, needless to say, I had to take my car to a carwash straight from the dealership!