Oh, beautiful man! When I bought my first Supra, I had to fight tooth and nail to unwind the deal. I had to dig deep legally and argue for 4 days straight.
It's called to Unwind the deal.
You can threaten to go to the DMV to report them that they sold you a damaged/lemon car, but I think it only works if your car is legit a lemon and not a small ding. I would have asked for a heavier discount