I hope the Philly car dealers are better about letting you charge the car than down here. I've been told several times that only $2000-$3000 of the price can be charged. Guess the credit card fee for the whole thing is about what the salesperson's commission is.
Maybe if you're buying a big honking SUV they'll be more willing. I've seen some 2 for 1 adds on those and fancy pickups down this way.
Jim