Petrol prices: cost compared at Asda, Tesco, Sainsbury's and Morrisons as stores accused of overcharging

Drivers across the UK have paid £1billion more for petrol and fuel at supermarket forecourts according to a new investigation by the Competition and Markets Authority (CMA).

The so-called 'Big 4' group - ASDA, Tesco, Sainsbury's and Morrisons - have been criticised by both the watchdog and the UK government for overcharging drivers, with the averge price margins at the retailers rising by 6p per litre between 2019 and 2022. The CMA has said that the price increases have continued as a result of poor competition at the pump.

Watchdog chief executive Sarah Cardell said: “Competition at the pump is not working as well as it should be and something needs to change swiftly to address this. Drivers buying fuel at supermarkets in 2022 have paid around 6p per litre more than they would have done otherwise due to the four major supermarkets increasing their margins.

“This will have had a greater impact on vulnerable people, particularly those in areas with less choice of fuel stations. We need to reignite competition among fuel retailers.”

According to the new report by the CMA, the price of diesel has cost drivers an extra 13p per litre during the first five months of 2023 for the same reason. Asda was also fined £60,000 by the CMA for failing to provide information relevant to the investigation in a timely manner.

A spokesman for Asda said that the fine was relating to “two individual alleged technical breaches” in relation to the way in which information was shared. The spokesman also said that the store "engaged fulsomely" with the inquiry.

NationalWorld has crunched the data to find out just how much the 'Big 4' supermarkets are charging for petrol on average across the UK.

How much does petrol cost at UK 'Big 4' supermarkets?

According to data from PetrolPrices.com, Asda tops the group for the highest average price for unleaded petrol at 142.9p per litre. Meanwhile, Morrisons took the title for the highest average diesel price across the UK, at 158.86p.

This marked a dip from the UK average petrol prices from around one year ago, with unleaded sitting at 190.32p according to the RAC Foundation. Diesel prices sat at an average of 199.02p at the same time.

However, while prices have slowly dropped, they still remain stubbornly high compared to the past three years. According to the RAC Foundation, current unleaded and diesel average prices - 144.01p and 145.59p respectively - are at around the same level as they were in October 2021.

We also used the Confused.com website and searched for cheap fuel within a 10-mile radius of five major city centres across the UK on July 4. Cities included in the data were Glasgow, Liverpool, Birmingham, Cardiff and London and prices are correct as of 28 June.

Across the four major supermarkets, NationalWorld found that Asda, despite taking the top spot for the highest average unleaded price, won the battle for the cheapest price at the pump with one station in Glasgow selling unleaded petrol for 137.7p.

What has the government said about petrol prices at supermarkets?

The government is hoping to crackdown on overcharging on supermarket forecourts by introducing a new law which will force fuel retailers to publish accurate and up-to-date prices and provide the data to third parties, such as price comparison apps. At present, access to public data on petrol prices is somewhat restricted.

Chancellor Jeremy Hunt said: “It isn’t fair that businesses are refusing to pass on lower prices to protect their profits while working people struggle with balancing their budgets.

“Consumers need to be treated fairly, and so we’re empowering drivers to find the best prices possible for their fuel by taking swift steps following the CMA’s recommendations.”

Energy Security Secretary Grant Shapps said: “Some fuel retailers have been using motorists as cash cows. They jacked up their prices when fuel costs rocketed but failed to pass on savings now costs have fallen. It cannot be right that at a time when families are struggling with rising living costs, retailers are prioritising their bottom line, putting upwards pressure on inflation and pocketing hundreds of millions of pounds at the expense of hardworking people.

“Today I’m putting into action the CMA’s recommendations and standing by consumers. We’ll shine a light on rip-off retailers to drive down prices and make sure they’re held to account by putting into law new powers to increase transparency.”