Many stations have a 'Club Card' or a customer loyalty card. Basically you can save 1-3 cents per gallon by signing up for them and using it each time you tank up.

Well this is a good discount but some places have taken it a bit further. Food Stores that have gas stations in their lot now have similar programs but you earn points by shopping in their store as wells. I spent my months groceries in the one store and earned enough points for 5 free gallons(with purchase of course) at the end of the month. Plus earning more point each time I fueled up there.

So Check into the discount cards. They may seem to have a higher price, but after you use the card its close to most competitors.