Only buy or fill up your car or truck in the early morning when the ground temperature is still cold. Remember that all service stations have their storage tanks buried below ground. The colder the ground the more dense the gasoline, when it gets warmer gasoline expands, so buying in the afternoon or in the evening....your gallon is not exactly a gallon . In the petroleum business, the specific gravity and the temperature of the gasoline, diesel and jet fuel, ethanol and temperature is a big deal for this business. But the service stations donot have temperature compensation at the...