More than a quarter of motorists are restricting the amount they spend when they fill up their car due to high fuel prices, an AA/Populus survey showed.
Women are restricting their petrol spending more than men, with budget-tightening happening the most in Northern Ireland, north-west England and Wales.
Of the 15,860 AA members surveyed, 14% paid a set amount on their credit card for fuel and 14% set a limit when they paid cash.
The number setting limits on fuel payment rises to 44% among unskilled workers, the long-term unemployed and pensioners.
Only 21% from the top socio-economic group are limiting what they pay at the pumps.
Among those budgeting a set amount for buying fuel, 23% have had to raise their limit, 13% have had to cut back on their spending and 29% are using their car less.
AA president Edmund King said: "This AA research is a stunning indication of just how badly fuel prices are affecting so many drivers across the UK.
"It is little wonder when you consider that £30 spent even at peak prices in 2008 (119.7p a litre) bought 25.1 litres of petrol. A year ago, the same amount bought 25.9 litres and now it buys 22.3 litres."
He went on: "With an average new car covering 9.6 miles per litre, the £30 spend buys around 34.6 fewer miles than a year ago.
"Consumers are cutting out one in 20 trips, shopping closer to home, combining trips and watching pump prices like hawks. Some are putting their lives and those of others at risk of grinding to a halt by running on fumes."