a lot. You got 5% credit on every purchase up to a maximum credit of $1000 per year ($20,000 in purchases). You could accumulate up to $7000 in credit to be used towards the purchase of any GM vehicle. Since I was traveling a ton back in the day, it was very easy to accumulate the maximum $1000 per year just on travel related purchases which were all reimbursed. It was free money to me.
In 1998, we bought a Chevy Prizm (essentially a Toyota Corolla) and got $7000 off. In 2005, we bought my oldest son a Chevy Cobalt and got $7000 off. In 2112, we bought my youngest daughter a Chevy Cruze and got $7000 off. Shortly after that, GM changed the rules and started limiting how much credit could be applied to a car purchase depending on the car model. They still tried to sell it as a good deal because then the amount of credit you could accumulate annually was unlimited. Yeah, right, let me accumulate $5000 in credit each year and then limit me to using $2500 in credit on such and such a car. No thanks. We quit using the GM card when they made that change and switched over to Marriott Visa. Tons of points were accumulated there since I always stayed in Marriott brands while traveling.
At the end of the day, I got $21,000 free money from GM 🙂