The findings are the result of an urgent market review commissioned by Kwasi Kwarteng, the Business Secretary, after concerns that the fuel duty cut announced in March has not been delivered “in any visible or significant way”.
The cost of filling up the average family car recently climbed above £100 for the first time despite a 5p cut in fuel duty.
The competition watchdog has defended petrol retailers, saying they have largely embraced the tax cut.
But the CMA has raised concerns about it rural drivers pay more than those in urban areas. It now plans to conduct a more in-depth review of the market, from refining to forecourt. It will look at differences in lobby prices between urban and rural areas and refining margins.
Sarah Cardell, general counsel at the CMA, added: “While there is no escaping the global pressures driving up fuel prices, the widening gap between the price of oil and the wholesale price of petrol and diesel is cause for concern.
“Now we need to get to the bottom of whether there are legitimate reasons for this and, if not, what can be done to address it.”
Mr Kwarteng said he welcomed the CMA’s decision to launch a comprehensive study. “Road fuel costs remain a significant part of household and business expenditure,” he said. “With this in mind, it is essential that competition works to maintain prices.”