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 petrol is; when it gets warmer, petrol expands, so buying in the afternoon or in the evening means your litre is not exactly a litre. In the petroleum business, the specific gravity and the temperature of the gasoline, diesel and jet fuel, ethanol and other petroleum products plays an important role.

A ten-degree rise in temperature can make a significant difference. But fuel stations do not have temperature compensation at the pumps.

When you're filling up, do not squeeze the trigger of the nozzle to a fast flow. If you look you will see that the trigger has three stages: low, middle, and high. In slow mode you should be pumping on low speed, thereby minimizing the vapours that are created while you are pumping. All hoses at the pump have a vapour return. If you are pumping on the fast rate, some other liquid that goes to your tank becomes vapour. Those vapours are being sucked up and back into the underground storage tank so you're getting less fuel for your money.

One of the most important tips is to fill up when your fuel tank is HALF FULL or HALF EMPTY. The reason for this is, the more petrol you have in your tank the less air occupying its empty space. Petrol evaporates faster than you can imagine. Petrol storage tanks have an internal floating ceiling. This ceiling creates zero clearance between the petrol and the atmosphere, so it minimizes the evaporation. However, the downside of this is by running with a full tank your engine is pulling more weight ans so fuel economy will not be as good.

Another reminder, if there is a tanker truck pumping into the storage tanks when you stop to buy fuel, DO NOT fill up. It's most likely the old fuel 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.