The firm’s data reveals that in the last 12 months a motorist has put the wrong fuel in their car approximately once every four minutes, equating to as many as 123,000 vehicles a year in.

The cost of wasted fuel and repairs alone ranges from £200 up to £2,500 in severe cases where rectifying the mistake involves replacing fuel filters, diesel pumps and diesel particulate filters. However, this can be the tip of the iceberg once roadside recovery or garage call-out fees (£100-150), refilling the tank (£100), not to mention lost work or leisure time, extra transport costs and the inconvenience involved (approx. £150) are added.

Rory Carlin from Halfords Autocentres said the problem comes as a growing number of motorists switch to diesel-powered cars, which are now more refined than they used to be.

‘Our garages see significantly more mis-fuelling cases during March and September – the peak months for new car purchase – than any other, which is largely made up of new vehicle owners who aren’t yet used to driving a diesel and have consequently made a mistake at the pump.’

He added: ‘Our advice to any motorist who realises that they have put the wrong fuel in their car at the pump is not to attempt to drive off. If you have already driven away before realising your mistake, stop as soon as it is safe to do so because circulating the incorrect fuel can cause further unnecessary engine damage.

‘Of course the best thing would be not to do it in the first place and Halfords stores sell “Diesel Only” stickers which costs less than two pounds and might just jog your memory in time to save you thousands.’