Van drivers could be adding up to £1.3 billion to their annual fuel bill, because their tyres are under-inflated, it has been claimed. In a study by Kwik-Fit it was found that 46 per cent of vehicles in the UK are driven with at least one under-inflated tyre.

According to tests, this could waste up to eight per cent more fuel and increase the amount of carbon emissions, which may encourage van insurance customers to act.

The figure has doubled since last year when only 20 per cent of those vehicles tested were found to have under-inflated tyres.

Kwik-Fit has blamed this increase on the fact that garages with fully functioning tyre gauges are on the decline.

David White, customer services director at Kwik-Fit, said: "It's disappointing that despite the extra financial pressure on motorists, this year's spot check found that the number of under-inflated tyres more than doubled in the past year."

Last month, the Times reported that drivers could save fuel by driving more slowly, pumping up the tyres and losing unnecessary weight from the vehicle.