2 tips for filling petrol and diesel:-

Only buy or fill up your car or bike during early morning, when the ground temperature is still cold. Remember that all service stations have their storage tanks underground. . The colder the ground, the more dense the fuel. When it gets warmer, petrol expands. So, buying in the afternoon or in the evening, your liter is not exactly a liter. In the petroleum business, the specific gravity and the temperature play an important role. 1 degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.  Another most important tip is to fill up when your tank is HALF FULL. The reason for this is, the more fuel you have in your tank the less is the air occupying its empty space. Petrol evaporates faster than you can imagine.