Every year 150,000 motorists put the wrong fuel in their car, of which 95% are diesel drivers, according to the British Insurance Brokers' Association (BIBA).
BIBA pointed out that the cost of repairs after misfuelling could range from £300 to more than £5,000, while nearly one in three car insurance firms do not pay such claims as it is not included in the policies.
The association called upon motorists not to start vehicles in the event of misfuelling and to immediately inform the petrol station and insurance company.
It said that insurance companies may deem motorists running the vehicle with wrong fuel a failure of policyholder's duty and refuse to pay out.
BIBA advised motorists to buy an adequate and comprehensive car insurance policy and not purchase solely on price alone.
Graeme Trudgill, BIBA Technical and Corporate Affairs Executive, said: "Nobody is immune to misfuelling, from TV celebrities like Philip Schofield to Wayne Rooney's reported misfuelling mishap, it is easily done.
"It is important to speak to your insurance broker to arrange a fully comprehensive policy that covers these unexpected risks."
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