you are about to fuck yourself extremely bad if you do .you will wind up with so much negitive equity in that car it will never get paid off and you will carry that negitive equity over to the next car you trade it in on and get fucked again.if you have no choice and have to get a car this way buy the least expensive car you can and make sure its not a terd.at least that way you have a chance at paying it off fairly soon.if not you will be in a cycle of debt that you will never break.

just my .02

good luck