Which side of my car is the fuel filler cap on? This design feature means you’ll never forget again

DRIVERS often pull up to a fuel pump only to find that their car's filler cap is on the other side.

It's especially frustrating for motorists using fleet or hire cars, or people who have recently bought a new car.

But there's no need for it to be a mystery, as car designers have included this neat trick on almost all makes and models that prevents confusion when refuelling.

What symbol on a car tells you which side the petrol cap is on?

There is a handy reminder on almost all cars that lets you know which side of the vehicle you should refuel it from.

On the fuel gauge on the instrument panel, there's a little icon of a petrol pump.

Next to the icon is an arrow, pointing either left or right.

If it's pointing to the left, your car's filler cap is on the left, and if it's pointing right then the cap is on the right.

In some cars, this information is represented with a fuel pump graphic clearly to the left or the right of the gauge.

What happens if I lose my petrol cap? Can it do damage to my car?

If the petrol cap falls off your car, or if you forget to return it, you risk losing fuel from the tank.

This will mostly be due to evaporation, as the tank has been designed to prevent significant sloshing, but it could happen.

Not only is this a waste of fuel but it may cause a hazard to other road users, especially if your car runs on diesel, which is very slippery when spilled on tarmac.

It could also generate an error in your car's fuel system, causing the "check engine" light to come on.

Debris and moisture could fall in to the tank, though this should be stopped by filters.

Your biggest risk is from fuel theft, as a missing cap makes it easier to steal petrol or diesel from a parked car.

Driving without your fuel filler cap, especially temporarily, is unlikely to cause damage to your car, but should be avoided.

Why are fuel filler caps on different sides of each car?

There are lots of reasons why a car maker might choose to put the fuel filler cap on the left or the right side of the car.

Sometimes these are to make it safer to refuel the car from a jerry can at the side of the road, so that somebody who has broken down doesn't need to stand in traffic.

Other times it's for mechanical reasons - for example, to make it easier for a cable-release fuel flap to be operated from the driver's side, or to make room for a sliding door on a van.

Sometimes these decisions reflect expectations in the manufacturer's domestic market.

Under car design regulations, the filler cap must be protected by the structure of the vehicle, to prevent fires in a collision. This is why the filler cap can't be in the middle at the very back of the car.