I'm 19, I have NO credit, co-signer with bad credit, can I get out of the 24% interest rate?

I understand it's a game the car dealers are playing. I live in florida. My parents have bad credit, I don't have any sort of credit. Is there something I can do to make them back down just a little on the rate? I'm really in love with this car, and I think they can tell. I just don't want to give in to their raping of what they call an interest rate.