FLEETS are being warned that filling up vehicles with the wrong fuel could become even more costly as car manufacturers clamp down on driver attempts to claim on the vehicle’s warranty.

Estimates are that up to 120,000 vehicles every year are given the wrong fuel – and that the problem is getting worse as the popularity of diesel soars.

Mike Waters, head of market analysis at fleet and fuel management company Arval, said: ‘The increase in the number of diesel vehicles has resulted in a dramatic increase in the number of absent-minded drivers putting the wrong fuel in their car.

‘Typically, there is a high occurrence of ‘wrong fuel fill-ups’ in the first few months of new vehicle ownership when the change in fuel type temporarily slips the driver’s mind.’

A result of this, he adds, is that vehicle manufacturers are being increasingly vigilant about motorists trying to avoid responsibility for their mistake by claiming on the vehicle warranty.

He added: ‘Ultimately, this could mean higher costs for fleets, should the subsequent warranty claim be rejected.

‘Most vehicles carry a label on the fuel cap to remind the driver of fuel type but we recommend that another label is placed on the dashboard, particularly during the first few months of ownership.’