Drivers have “a right to know” why they are still being charged record prices to fill up, according to the RAC.
The AA said drivers are “being taken for fools by retailers”.
Figures from data firm Experian show the average price of a litre of petrol at forecourts in the West Midlands reached a new high of 191.2p on Tuesday.
The average price of diesel was 199.0p per litre, a fraction of a penny below the record of 199.1p per litre set on Saturday.
RAC fuel price spokesman Simon Williams said: “Inexplicably, fuel prices rose yet again yesterday.
“We can see absolutely no rhyme or reason why average forecourt prices are still going up, given that the wholesale price of both fuels has been falling for weeks.
“Drivers up and down the country have a right to know why they’re having to pay what they are for fuel when the costs to retailers right now are so much less than they were a few weeks ago.”
A 5p per litre reduction in fuel duty implemented by the Treasury in March has not stopped pump prices from soaring.
Earlier this month, the Competition and Markets Authority launched a “short and focused review” of how much drivers are being charged for fuel after a request by Business Secretary Kwasi Kwarteng.
Chancellor Rishi Sunak told MPs on Tuesday he will carefully consider calls for a “more substantial” fuel duty cut.
Amid concerns the previous reduction “didn’t really touch the sides” for hard-pressed drivers, he said he would take the recommendations “under advisement” when challenged in the House of Commons.
Mr Williams said a cut in pump prices “really can’t come soon enough”.
He went on: “If it’s a further fuel duty cut that the Chancellor decides on, it’s absolutely vital that this is passed on in full immediately by retailers to give drivers some respite from these historic high prices.
“It’s also vital the Government monitors the wholesale market and closely scrutinises retailer margins.”
Jack Cousens, head of roads policy for the AA, said drivers are “being taken for fools by retailers”.
He continued: “With the Prime Minister and the Chancellor talking openly about the prospect of cutting fuel duty further, drivers need to hear less talk and see more action.
“An additional 10p cut in duty, which the AA called for weeks ago, will not only help ease the pressure at the pumps but keep prices in supermarket aisles down too.
“Until this happens, household budgets across the country will continue being squeezed.”