By bizn_fun 
Petrol was 136.8p per litre last week, according to government tracking, external, while diesel was 146.1p per litre.
The CMA report, external found that fuel prices had fallen “significantly” since it last studied the issue in 2023, largely due to lower oil prices.
However, it said profit margins on fuel for both supermarket and non-supermarket retailers were “historically high”.
“Average fuel margins on a percentage basis have continued to increase for both supermarket and non-supermarket retailers,” it said.
The report noted fuel retailers’ arguments that their operating costs had increased, but if this were the case, “we would expect to see this reflected in declining profit margins”.
The CMA said if there was more competition, drivers would see better fuel prices at the pump.
Retailers will have to sign up to the planned fuel finder scheme and report price changes within 30 minutes of them being implemented.
The CMA said the finder would be accessible through apps and satnavs, and allow drivers to easily compare prices.
“In turn, this should incentivise retailers to compete harder for customers, placing downward pressure on prices.”
Dan Turnbull, senior director of markets at the CMA, said: “Fuel margins remain at persistently high levels – and our new analysis shows operating costs do not explain this.
“We know fuel costs are a big issue for drivers, especially at this time of year with millions making journeys across the country.”