Möglichst randvoll tanken
The fuel comes out of the tank at 6 - 8 ° C and has a certain volume according to this temperature. If the outside temperature is higher, the fuel in the tank immediately starts to heat up. This increases its volume. When the fuel nozzle stops, there is still enough air in the tank, which can escape as the fuel expands. I fill up to the brim, then this air cushion is missing. The fuel expands and the part that no longer fits in the tank exits.