Check your local laws but I think most states have a law that a signed contract is not binding for 72 hrs . That is not something merchants don't want you to know about but it does give the consumer time to think about the situation with a clear mind once you are away from the dealership .

I know NY doesn't have a cooldown period, and out of state purchases are not subject to lemon laws. Again, search for "bimmersbenz" and read more :(