Not sure where you live, but here in Michigan, you can get a lot of money off of your gas by purchasing gift cards at Kroger.
For example, if you buy a $200 gift card, that equals 400 Kroger points. At a Kroger gas station, that equals 40 cents off per gallon of gas for one purchase.
I paid for a whole trip to Disney this way and saved a lot of money on gas too!