Motorists have seen little or no benefit from the recent fall in crude oil prices, the AA said today.
A 7% drop in the value of the pound against the dollar since August has denied drivers the possibility of a 2p per litre price cut on petrol, the motoring organisation said.
Prices dipped around 1.5p in August but have climbed again to leave prices of both petrol and diesel within a fraction of their all-time high seen in May, even though the market prices of crude oil have fallen by more than 10%.
The cost of a litre of petrol is now 135.61p while a litre of diesel is 139.62p, meaning there has been none of the usual downward move following the end of the summer driving season, said the AA.
President Edmund King added that the price of Brent crude was also 10 US dollars a barrel out of line with the US equivalent of light crude, something that was potentially worth 5p a litre to UK motorists, he said.
"Current fuel prices would be worse were it not for UK supermarkets' traditional lag in passing on higher wholesale costs."
He added that money-off-fuel vouchers had given consumers with smaller budgets access to fuel discounts.
However, Mr King said: "UK families remain hostage to fuel price movements that buck traditional trends, and oil prices that don't even make sense to experts in the market," he added.
Compared to a year ago the AA estimates £12.6 million a day is being "siphoned" away from the high street and other spending into fuel sales.
The industry points out that some 60% of the pump price is accounted for by fuel duty and VAT, with another 10% going on delivery costs, marketing and profit margins.
A year ago, petrol averaged 115.07p a litre and diesel stood at 117.54p, meaning a typical 50-litre tank now costs £10.27 more. A school run of just 1.5 miles is costing £40 a year more, the AA added.