Small tips when buying gasoline. 1) Only buy or fill up your vehicle/car during early morning, when the ground temps are still cold. [This applies to Northern and New England States mostly.] The colder the ground around underground storage tanks, the more dense the fuel. When it gets warmer, petrol expands. Buying in the afternoon or at night, therefore, a liter is not exactly a liter. Specific gravity and temp play an important role. 1 degree rise in temp is a big deal; service stations do not have temp compensation at the pumps. 2) Fill when tank is HALF FULL. The more fuel you have in the tank, the less is the air occupying its empty space. Petro evaporates faster than anyone can imagine. 3) If a fuel truck is pumping into the storage tank when you stop, DO NOT fill up--most likely the petro or diesel is being stirred up as the fuel is being delivered, and you might pick up some of the dirt that normally settles on the bottom. I got dirt in a tank once, and it ruined the car.