Drive Time DT credit, Ugly Duckling sold me a piece of crap car! Columbia, South Carolina

Based on your post, the vehicle is way upside down. If you trade it for another, the amount of negative equity doesn't just go away. It is added to the next vehicle loan unless you have the cash to pay off the negative amount. Certainly its worth checking the value of your vehicle and the payoff balance so you know the actual figures.

 If you don't have the money to pay it off, and you decide to just give the car back, then it will go on your credit report as a repo. Once you have signed the car note, you are stuck with it until pay off or successful trade. By successful trade, I mean one that isn't going to bury you in payments that are too high for your budget. I don't work for any dealership. The information above is how vehicle loans work. Of course, you can always get out of the vehicle note by paying it off.

One last thing: it might be cheaper and better for you to take the car to another more experienced mechanic to see if he can get it in better shape for you. Good luck with getting this problem worked out.