Petrol and diesel prices continue to climb to new highs, figures show.
Statistics from data firm Experian Catalist show the average cost of a litre of petrol at UK forecourts on Wednesday was 168.2p.
That was up from 167.6p per litre on Tuesday.
Diesel prices reached an average of 181.0p per litre on Wednesday, up from 180.9p a day earlier.
The Competition and Markets Authority warned on Wednesday that retailers could be fined if it launches a formal investigation into the sector, following claims they have hiked profit margins since a cut in fuel duty.
RAC analysis found retailers’ average profit margins for a litre of petrol and diesel are currently 11p and 8p respectively.
In the month up to the 5p per litre duty cut on March 23, it was 9p for petrol and 6p for diesel.
RAC fuel spokesman Simon Williams said filling a typical 55-litre family car with petrol costs an average of £92.53, while the bill for a diesel car is “teetering on the brink of £100” at £99.55.
He went on: “So far in May, a litre of unleaded has rocketed by more than 5p a litre and diesel by 3.5p.
“Since the start of the year it’s a far bleaker picture as petrol is 22.5p higher and diesel an astronomic 32.0p.
“While wholesale prices dropped on Wednesday, indicating we may have passed the peak, drivers should brace themselves for further pump price rises as retailers who have had to buy new stock this week pass on their increased costs in the coming days.
“Drivers badly need further help from the Government, particularly as the Treasury is benefiting considerably from the windfall that 20% VAT brings them on these record high prices.”