That sucks balls. It sounds like you've signed all the paperwork officially abolishing them of any responsibility. I would suspect the CEL was obviously on because of the transmission slippage storing a fault code. It couldn't hurt to atleast try for something and approach the salesman in a direct, yet polite manner and explain what's happened. What was this 300 dollar sensor he was speaking of? I try my best to hope that salesman don't knowingly screw locals so badly but who knows. It does sound like they were very upfront about the fact that the vehicle hadn't even been inspected pror to sale. I hope you at least got a great deal on the X5.

There's a saying a guy I used to work with told me one time that was related to Mercedes- "There's nothing more expensive than a cheap Mercedes" Of course that would apply to BMW As well. Again, I hope you got it dirt cheap since they apparently didn't put any money into refurbing before resale. Sounds like they just stuck it out on the lot. Sounds like you'll be dropping some serious cash soon. Maybe you can appeal to some good natured intention on their part and at least get something out of the deal. Good luck..

-Ben