MORE than 100,000 drivers a year are putting the wrong fuel in cars, costing businesses millions of pounds in call-outs and lost working time.

Figures supplied by the breakdown services suggest that the problem of mis-fuelling is reaching epidemic proportions, with nearly twice as many call-outs for mis-fuelling as those for running out of fuel, according to Green Flag.

The AA estimates it has 45,000 call-outs a year due to mis-fuelling. The RAC has 70,000 fuel-related call-outs annually, with at least half likely to be from mis-fuelling. Call-out fees alone are costing about £7 million a year. But if working time lost was factored in, the cost to UK business fleets would be tens of millions of pounds.

A spokesman for Green Flag warned fleets that drivers using pool or hire cars were particularly susceptible and that high quality diesel cars were adding to the problem. Drivers were literally forgetting they were driving diesel cars and filling them with petrol.

Fuel retailers claim they are working to try to stem the flow of fuel into the wrong tanks. Diesel and petrol nozzles are now standardised colours – green for petrol, black for diesel – and signage has been improved to avoid confusion.

However, despite improvements at the pump to limit confusion, the number of mis-fuellings is not diminishing. Experts put it down to the surge in the number of drivers opting for diesel cars for the first time but who are still visiting petrol pumps.

A spokesman for the UK Petroleum Industry Association said: 'The vast majority of mis-fuelling is petrol into diesel. We will be looking at launching an education campaign next year to make drivers more aware of the problem.'

He urged fleet managers to press home to drivers the extent of the problem, through initiatives such as putting stickers on fuel gauges, particularly of cars that are used by a number of different people.

The fuel retailers are also looking at long-term solutions such as microchips that recognise the type of fuel about to be delivered, or a voice that asks the driver if they are sure they want to use diesel when they take the nozzle out of its housing.