The whole idea of applying is to save money. Whenever you make a purchase, you never want to pay full price and with a gas credit card, it will be like you're getting g a sale every time you fill up a pump. The cards work in a very simple way. Every time you fill up at the pump, you're going to get a certain percentage off your final total. This percentage will vary from card carrier to card carrier but the industry average is anywhere from one percent to ten percent. This number, of course, can go up over time depending on the credit market.