Most gas stations are independently owned and don't even necessarily sell gasoline from the oil company they brand themselves as. They also make most of their money on stuff you buy in the convenience store and essentially break even on the gasoline. It's just there to get more people into the convenience store.

That said, there's a BP and a Mobil right near each other by my office and the Mobil has been looking way busier than the BP lately. They both have 2 Rockstars for $3 so I switch off which one I go to so as to seem like less of a caffeine fiend. h: