Back in the '90's the GM card was 5% on every purchase, unlimited. I accrued $4200, called and got a certificate sent to me, went through the normal negotiation to arrive at a good price, and then handed over the certificate. They didn't bat an eye. List price ~$24K, out the door with $17K on a fully loaded Pontiac Grand Prix back in 2000. I got lucky, that was a great car. Lasted me 9 solid years, over 200K miles.