ooh, what audi you got then? A3 I'm guessing? Year etc.. pics? Second car isn't realy worth it for pizza delivering as the money you're getting from the pizza place will really just cover your insurance on the second car, not to mention buying it. Your best bet, to do it, would just be to get insured on your parents car as a second driver, if they don't mind you doing it.. but I'm guessing they will.
Careful though, 'cause I know someone that got done for no insurance by delivering pizzas. His insurance didn't cover him for that as he was only insured for SD+P and not business use.