The cheapest supermarket to fill up your car with petrol has been revealed—and you could save 4p a litre. Drivers could slash £2.20 from a 55-litre family car by filling up at a UK supermarket that is “considerably cheaper” than competitors.
Over a year, a motorist refuelling once a week would pocket £114 in savings. Supermarket forecourts charge 131.5p on average per litre of petrol and 139p for diesel—both nearly 4p below the UK averages. The most affordable right now is Asda, priced at 131p, with Sainsbury’s, Tesco, and Morrisons trailing behind for the top spot.
According to the RAC, the most economical supermarkets to fill up your car with diesel are Asda (138.7p), Sainsbury’s (139.0p), Tesco (139.1p), and Morrisons (140.0p).
RAC fuel spokesperson Simon Williams said: “Unfortunately, drivers heading into the busy summer holiday season will be met with rising prices at the pumps, as the cost of fuel increased in July for the second month running.
“While the average price of petrol for the year so far is just a couple of pence above the average for all of 2021, drivers are still meant to be benefiting from a 5p-a-litre fuel duty discount (52.95p as opposed to 57.95p) which has been in place since the start of the Ukraine War in early 2022.
“Our analysis of the difference between wholesale and retail prices shows retailer margins remain high, particularly on petrol. This is emphasised by the fact that the average price of unleaded in Northern Ireland is 7p cheaper than the average across the UK.
“Drivers may also see significant differences on forecourt totems from area to area, which can be very frustrating.”
The RAC explains that the UK average pump prices quoted are based on Competition and Markets Authority data from 1-31 July 2025.
It also states that its wholesale prices are taken from 1-31 July.