The Lex maintenance department, which spends around £50m a year on the upkeep of its 123,000 vehicle fleet, is seeing repair costs range from £300-£3,000 depending on the type of diesel engine fitted to the car.
Most at risk are the modern common rail diesels which are built to more exacting tolerances than standard diesel engines. If petrol fuel gets into the common rail diesel system it can mean replacing both low and high pressure fuel pumps, injectors, rail, line filters and tanks, which can easily cost a few thousands pounds to fix.
"The cost of the repair depends on whether the driver has simply started the engine or they have driven it for a few miles with the wrong fuel in the system. The longer the petrol has been in the system, the more money it will cost to repair," says Jamie Wiseman, Lex Vehicle Leasing’s maintenance manager.
"Manufacturers are now giving their dealers detailed advice as to which stage the mis-fuel has reached and the correcting action they must take. We had two Mercedes common rail diesels to repair recently which cost £3,000 per engine," he added.
All costs to repair mis-fuels have to be met by the consumer as manufacturer breakdown cover does not cover mis-fuels, although they are likely to come out to your car and take it to the nearest dealership. Also if a car is on a PCP or contract hire agreement it will still be up to the driver to pay for the damage, rather than the finance company.
Lex is advising drivers to adopt the same principles as rental companies where the car’s fuel access flap is labelled with the relevant fuel type, or a relatively discreet label is put inside the car.
"When repairs are costing up to £3,000 it’s worth drivers taking some precautions to prevent them from mis-fuelling. Rental companies have seen mis-fuels come down significantly by taking these precautions so it’s worth the investment in clear labelling for the driver," said Wiseman.