Ford's Easy Fuel system, which prevents the expensive mistake of mis-fuelling, is also proving a deterrent to petrol and diesel thieves.

The escalating value of fuel has led to thefts from vehicles in the UK increasing by 25 per cent in the past year to a reported 4,500 cases annually.

While Ford Easy Fuel – fitted as standard to top-selling models including Ford Fiesta, Ford Focus and Ford Mondeo – was designed to make refuelling simple and error-free, it also makes siphoning extremely difficult.

"Our novel Easy Fuel feature ensures that Ford owners put the right fuel in their car," said Andy Barratt, Ford Britain Sales Director.

"Another customer benefit is that it acts as a deterrent by slowing down the fuel thief."

The technology behind Easy Fuel adds extra layers of security behind the external fuel filler opening, which is already secured as part of the vehicle's central locking, to inhibit forced entry and siphoning.

Easy Fuel's spring-loaded flap is held closed by two latches that can only be released by a standard-size fuel nozzle.

When the proper nozzle is inserted into the filler neck of the system, the latches release and the nozzle pushes the spring-loaded flap to the open position.

When the nozzle is removed, the flap is automatically and firmly closed by the spring.

Easy Fuel also has a patented inhibitor designed to prevent improper fuelling and siphoning.

The inhibitor consists of a fuel nozzle detector that guides the nozzle to the opening.

If a nozzle or foreign tube of a different size – a diesel nozzle or plastic hose, for example – is placed in the filler neck of a petrol-powered vehicle, the latches will not release.

For a diesel-powered vehicle, the inhibitor will keep out the smaller nozzles.