Rising fuel prices and increases in interest rates mean motorists are paying an average of £101.75 a week to run their cars, the RAC claims. The price rises are so severe that the motoring group says owning a car may soon be a luxury many cannot afford.

The £400 a month that British motorists are forced to pay on their cars is about a quarter of the average UK household income.

An RAC survey of fuel prices across the country found that unleaded petrol is now 5p a litre higher than in March and diesel has gone up by 4p. This will add £102 a year on the cost of fuel for the most petrol-thirsty cars, while interest-rate rises mean financing costs will be £94 more each year, says the RAC.

RAC Insure’s managing director, Nick Hall, says: "The rising cost of motoring is testing the mettle of British motorists. The monthly cost of running a car remains a quarter of all household income and about the same as the average person’s contribution to a family holiday - and the continued threats of increases in petrol prices, interest rates, taxation and insurance premiums cannot be ignored. We have to acknowledge that the idea of owning a car may soon be a luxury many cannot afford, and perhaps not be surprised that some break the law, such as driving uninsured, to cut their costs."

Motorists are likely to continue paying 80p a litre for fuel in the foreseeable future, the RAC says.

The Toyota Yaris, which runs at 28p a mile, will cost an average of an extra £53 a year in fuel, while the BMW 7-series will eat up £102 more fuel each year.

The RAC cost of motoring index - based on insurance information, fuel, servicing, depreciation, VAT and breakdown cover - found that the Volkswagen Golf costs an average of £96.98 a week to run, while the BMW 7-series costs £322.25. The average cost is £101.75.

However, the rate of depreciation has gone down.

The depreciation value of cars, such as the Vauxhall Corsa, Rover 25 and Land Rover Discovery, has slowed by £208 a year, meaning that these cars are holding their price better.