I don't know if it applies to all states. In Florida, Publix supermarkets have coupons for gas every few weeks. $50 gift cards for $40 with a $25 grocery purchase. It is presently running from August 11th - 17th. Coupons can be found on the weekly special printouts on newspapers or at the stores.

Stores locations are in Alabama, Florida, Georgia, South Carolina, and Tennessee.