BMW DRIVERS OWNERS!! I am planning on purchasing a M5 2006?

I am just curious to what you put down and how much you put down. How much are your payments per months, whats the price for repairs, what make is your car what color. What your interest rate is? How good is your credit.How should I go about this, I want to go to a dealer but I know I will get screwed. The car I have now is worth 2000 dollers in the kelly blue book and I think it will be worthless to finish my payments. I got finaced by this bank and that is how I got screwed. I am paying very high car payments and want to change my car for a BMW. Do you think they will want my car for a trade in? Cuz I know I dont.