So, you’re running low on petrol, on empty or just need a top-up. You head off to the filling station and become increasingly anxious as you see those numbers ticking over, higher and higher, as the petrol attendant tries to fill your tank to the rim.

We’ve done some research on this common practice and our findings are quite disturbing.

According to various sources, overfilling your petrol tank is not only bad for your car and your pocket, but for the environment as well.

Here’s the lowdown on overfilling:

The extra fuel may never even reach your petrol tank

Some sources believe that this fuel never even leaves the pipe of the fuel pump and simply gets pumped into the next vehicle. Thanks for that, Good Samaritan!

Most filling stations are also equipped with pumps that have vapour-recovery systems to recover petrol fumes from the air. The extra petrol may be drawn through this vapour-recovery system and go right back into the filling station’s tanks.

If this is true, you’re paying for fuel you’re not receiving!

Why is it bad for my car?

Just like filling stations, your car also has a vapour-recovery system. This evaporative-emissions system is designed to capture and collect fuel vapours from your tank, store them in a canister and then, upon start-up, introduce them into the induction system through an evap valve. This includes a small separate tank-within-a-tank in many vehicles, plus a charcoal canister and its plumbing. Overfilling could damage this system and lead to your car malfunctioning.

Fuel also expands as it warms up – something to keep in mind as summer approaches. As the fuel in your tank gets warmer, it expands and has to go somewhere. If you overfill your tank, it’s believed that this fuel can find its way into the vapour-collection system of your own car which can cause the system to malfunction and affect your vehicle’s efficiency.

Why is overfilling bad for the environment?

When your petrol tank is overfilled, it is almost a certainty that some fuel will evaporate or be spilled.

Petrol fumes add toxic substances, such as benzene, to the air. Can anybody say #GlobalWarmingAlarm? Fuel vapours can be detrimental to your health and are harmful if inhaled.

We’re no experts on this topic but we want to leave you with this last thought … Why would car manufacturers, who are experts, add the automatic cut-off function to your petrol tank inlet?

Something to ponder? Use it, don’t use it … Maybe next time the petrol inlet automatically cuts off, give your wallet a break and tell the attendant his job’s done!

Are you an expert or do you know more about this topic? We’d love to hear from you. Hit us up in the comment section below.