If you have ever talked to anyone that owns a gas station/convenience store, you will find that they typically net 3 cents or less off of every gallon of gas. They make their money with the stuff inside. The gas is the lure to get them into their store. Stations that have garages make their money on the services, and the gas is a way to "advertise" their garage. When a station has to buy gas at increasing prices, it can seriously effect the capital, and they typically raise prices on merchandise in the store. If the prices go too high and people stop buying the products, they are fucked.