BMW is now fitting its incorrect fuelling protection system (IFPS) to all diesel-powered models.

Ford is introducing a similar system on its models in Europe.

IFPS works by preventing the fuel filler nozzle of a petrol pump from entering the fuel tank neck of a diesel-powered car. The larger diameter diesel nozzle is able to touch two opposing contact patches that then release the locking system, allowing the nozzle to engage. A smaller petrol pump nozzle can not make the same connection and this access is blocked.

The system was initially introduced on some models last March, but is now also fitted to 6 and 7 Series and X5 models. Its introduction is expected to prevent most of the 1,000 cases a year of mis-fuelling that occur on BMW cars in the UK which can each cost owners thousands of pounds to rectify.

BMW reckons that 150,000 vehicles are mis-fuelled in the UK alone every year.