The poorest car owners in Britain are slipping further into ‘transport poverty’, a new RAC study suggests.

The RAC Foundation poll shows that in 2012 the least well-off car owners had a top weekly expenditure of £167, of which £51.40 was spent on running a vehicle.

These households spent at 31% of their disposable incomes on buying and running a car in the same year, up from 27% in 2011.

The car spending included an average £16.40 weekly cost for fuel, £6.10 for repairs and servicing and £9.50 on insurance.

While record numbers of workers now commute by car, the survey shows that the cost of transport is a big hurdle to taking up employment.

More than half of employees in the poorest areas of the UK drive to work, and there is little opportunity to cut their motoring costs further.

Professor Stephen Glaister, director of the RAC Foundation, said: "Before tax we have some of the cheapest petrol and diesel prices in Europe but when you add in fuel duty and VAT the picture changes dramatically.

"The Chancellor rightly points out that he has frozen fuel duty since March 2011 yet almost 60% of the pump price still goes into his pocket."

The figures were based on data obtained from the Office of National Statistics.