When the Tank in the car is fulled, the return valve activated and petrol flow back to the tank or sump below. 

Many of us are not aware that the petrol kiosk pump has a return pipe-line. When the petrol tank reaches full level, there is a mechanism to trigger off the pump latch and at the same time a return-valve is opened (at the top of the pump station) to allow excess petrol to flow back into the sump. But the return petrol has already passed through the meter, thats mean you are donating the petrol back to SHELL, PETRONAS, BHP, CALTEX and MOBIL.

Moreover having full tank of petrol you are actually carrying it around. Paying petrol to carry around another load of petrol does not make any economic sense right? So from today onward, pump half tank will do. Remember to email this post to your friend,,, click here..