German armour is complex.
All fuel tanks are interconnected. The system was filled at the center rear tank (with the filler cap) also the vent/breather lines are interconnected. All vents of the lower tanks lead via the higher positioned tanks to the filler tank.
The driver could select which fuel tanks provided fuel...rear left (top and lower tank), rear right (top and lower tank), or both tanks in the fighting compartment. Selecting the rear tanks included also the center filler tank.