At least 150,000 drivers mis-fuel every year - that’s one person making the error every three and a half minutes, according to the AA. British motorists are getting increasingly careless at

the pumps, and the number putting the wrong fuel into their car has doubled over the past ten years.

This creates 7.5m litres of contaminated fuel, or the equivalent of three Olympic-sized swimming pools. What’s more, drivers are pouring up to £750m of fuel down the drain every year.

Most incidents of mis-fuelling involve petrol being put into diesel vehicles. The AA says this is partly due to the wider diesel filler neck and narrower unleaded nozzle.

Another reason is the growing popularity of diesels - and people are

forgetting what type of vehicle they are driving because modern engines are less noisy.

The stats were released as the AA launched the UK’s first national service to help drivers who put the wrong fuel in their vehicle.

AA Fuel Assist is a specialist roadside service which travels to customers and drains, flushes and replenishes vehicle fuel systems, and the AA is investing about £1.7 million in the service.

Donald MacSporran, AA technical performance manager, said Brits have been getting much worse at mis-fueling, especially over the past five years.

“We have seen a significant growth in diesel car sales, and modern diesels are so quiet that people sometimes forget they’re driving one,” he said.

“You also have an increasing number of people owning more than one car, so it’s only too easy to absent-mindedly put the wrong fuel in.”

The service aims to get 99% of vehicles back on the road after the 45-minute fuel drain.

MacSporran added: “If someone realises they have mis-fuelled, they should ideally not start the engine, and call us for advice.

“Depending on the level of contamination, our technical team will advise over the phone if the vehicle can be safely driven but, in most cases, a fuel drain will be required. Although people always feel embarrassed, we try to lessen the pain by offering a speedy, cost-effective solution for the customer, as well as minimising the impact on the environment.”

He estimated that a repair bill after mis-fueling could cost up to £5,000 to £6,000 – or even higher – depending on how far it is driven after the error.

The AA Fuel Assist service operates Monday to Friday from 8am to 8pm and prices start at £176.25 (£150 plus VAT) for AA members and £199.75 (£170 plus VAT) for non-members.