You got screwed, but I think you already know that. I would have searched for a car elsewhere. I paid 1000.00 over invoice, but that was a year ago. I didn't receive the 4500.00 eco credit. That money came from BMW, not the dealership. That was BS they had to sell a certain number of vehicles before they got that credit from BMW. My buying experience wasn't much better and I won't go back there for service, or to purchase another BMW. They don't even have free bottled water at either of the BMW dealerships I've been to. My Lexus dealer has all kinds of snacks, bagels, drinks.
I was lied to as well at my selling dealer. My vehicle came in with 3 out of 4 of the wheels damaged during transport. The dealer said BMW would take care of it and they didn't. I had to force the dealership to replace my wheels. BMW only wanted to repiar my wheels. I did learn a lesson, don't trust the dealer, don't trust BMW to do the right thing. This very well might be my last BMW. This is my 4th BMW...

Craig