The poorest 10% of car-owning households in the UK are mired in transport poverty, according to the RAC Foundation.
These households are spending at least 27% of their disposable income on buying and running a vehicle, the foundation said.
In contrast, similar motoring costs among the wealthiest car-owning households represent only about 12% of their disposable income.
Typically, a “poor” car-owning households spends £44 a week on motoring out of a total seven-day expenditure of £167, the RAC Foundation said.
Of the £44, a total of £16 is used to buy petrol or diesel and £8.30 goes on insurance.
The foundation said it had based its figures on analysis of “previously unreleased” data from the Office for National Statistics.
RAC Foundation director, Professor Stephen Glaister, said: “We already knew transport was the single biggest area of household expenditure bar none, but this spending breakdown just for car-owning households is not normally available. It lays bare the truth about the extent of transport poverty in the UK.”
He went on: “The Budget is likely to tinker with the rate of fuel duty. For people already drowning under the weight of motoring costs, cutting a penny or two off the price of a litre of fuel will help, but is like rearranging the deck chairs on the Titanic.
“To make any meaningful difference to those on the lowest incomes, the rate will need to be cut much further.”