By Ian Barnsley
Families with low incomes are having to make cuts elsewhere to afford rising motoring costs, the RAC Foundation warns.
Its research found less well-off households that run cars found themselves deeper in "transport poverty" in 2012.
That year they spent an average 31 per cent of their incomes on buying and running vehicles that year compared to 27 per cent in 2011.
Office for National Statistics data shows struggling families spent no more than £167 a week on essentials in 2012.
Driving costs mount up
Of that expenditure around £51.40 involved their car - including £16.40 on fuel and £9.50 and £6.10 on insurance and maintenance costs respectively.
"These figures give the official picture of the financial sacrifices being made by the UK's poorest families to remain mobile," RAC Foundation director Professor Stephen Glaister said.
"Even though there has been some relief at the pumps in recent months and reported falls in insurance prices, it will have done little for those struggling to make ends meet.
"While record numbers of people now commute by car, this data shows the cost of transport is a big hurdle to taking up employment," Mr Glaister said.
Little opportunity to reduce motoring costs
"For the poorest car owners there is little opportunity to reduce their motoring costs further. They will already be driving as little as they can and will have cut back on things like maintenance.
"Nor are they likely to be able to afford to swap their car for a newer model with better fuel economy and reliability."
"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."