I don't know about that. I have the GM card already, and we just got $2500 off a brand new car for my wife. I only had $500 worth of earnings, but GM upped it to $2500 if we bought a car this holiday season. Well, we were interested anyway, and their $2500 was added to $2000 worth of rebates on the vehicle.
So, due to the GM card's incentive, I got $4500 off a brand new vehicle when we actually needed a new vehicle.
Heck, just sign up for the GM card and pay your DirecTV bill with it every month, which is what I was doing. GM will eventually throw in some bonus money and you'll get a great deal.
Get yourself a free I-pod, too? What a bonus!!!