Diesel rose by more than a penny from 154.68p to 155.99p (1.31p), making for three consecutive months of rises. A full 55-litre tank of petrol now costs £80.56 – up by £1 – and diesel £85.79, up 72p.
While the increase in forecourt prices was driven by a 5% rise in the cost of a barrel of oil (from $83.55 to $87.48) in March, a surge in demand for petrol in the United States ahead of the summer has caused the wholesale price of unleaded to rise to match that of diesel.
This meant that by the end of March, a litre of unleaded cost 113.3p on the wholesale market, only a penny or so less than diesel at 114.69p. If this remains the case, the gap between the two fuels at the pumps should close from its current 7p in the next few weeks.
RAC Fuel Watch data shows the increase in the cost of wholesale petrol has squeezed the average retailer margin which has now reduced to 8p a litre, in contrast to 10.5p at the beginning of the month. The average margin on diesel is 11p, up by a penny over the same period.
Looking at the big four supermarkets which dominate UK fuel retailing, Tesco had the cheapest unleaded on 31 March at an average of 142.7p across its 511 forecourts, while Asda had the most expensive at 145p.
Asda, which for many years prided itself on selling the lowest-priced supermarket fuel, also had a whopping 33p price difference between its cheapest and most expensive petrol.
The grocer charged 139.7p at nine of its forecourts, four of which are in Northern Ireland, and 172.9p at junction 29A of the M1 near Sheffield – a Shell-branded site operated by Asda.
Comparatively, Tesco had the smallest difference between its lowest and highest prices at just 6p (138.9p v 144.9p).
At the end of March Sainsbury’s sold the cheapest unleaded at 136.9p at two sites – one in Wolverhampton and one at Dungannon in Northern Ireland. Tesco, however, was charging its lowest price – 138.9p – at 30 separate forecourts. Asda, on the other hand, was only charging its lowest petrol price of 139.7p at nine of its 658 forecourts.
Sainsbury’s and Tesco were tied for the lowest average diesel price across their portfolios at 151.7p and 151.8p. Asda’s gap between its cheapest and most expensive diesel was 35.2p (147.7p at Guildford, Torquay and two in Northern Ireland v 182.9p at the Shell-branded site it runs near junction 29 of the M1).
Tesco had the smallest gap of just 6p between diesel at its forecourts (148.9p v 154.9p) while Morrisons was also under 10p (145.7p v 154.9p) Sainsbury’s had the cheapest diesel at 142.9p, but this was only available at Andersonstown, near Belfast, in Northern Ireland. Tesco’s lowest price of 148.9p was, however, on offer at 45 of its forecourts.
BP and Shell-operated forecourts also have very large differences between their cheapest and highest fuel prices. For unleaded BP has a gap of 27p (142.9p v 169.9p) and Shell 26p (143.9p v 169.9p) across their 287 and 536 forecourts. For diesel, it is 30p for BP (149.9p v 179.9p) and 26p for Shell (153.9p v 179.9p).
RAC fuel spokesman Simon Williams said: “The rising cost of oil, combined with the pound still only being worth a meagre $1.3, has led to another month of misery at the pumps with the price of petrol going up 2p a litre. Sadly, this means the average price of petrol has gone up nearly 6p so far this year.
“The RAC’s analysis of the fuel price data being compiled by the Competition and Markets Authority (CMA) shows that Asda is no longer the cheapest retailer as, at the end of March, Tesco had the lowest average petrol price across its 511 forecourts. It was also joint cheapest for diesel with Sainsbury’s.
“The data also reveals that Asda, Sainsbury’s and Morrisons only offer their cheapest prices at one or two stores whereas Tesco offers it at around 30 forecourts, albeit at a slightly higher cost. Its customers also have the comfort of knowing that there’s only 6p difference between its lowest and highest prices.
“Sadly, Asda appears not to be the force it once was in fuel retailing. Gone are the days when it used to announce big headline-grabbing pump price cuts when wholesale prices fell, along with a promise at the time that drivers would never pay more than a certain low price at any of its forecourts.
“The data from the competition watchdog also highlights the wildly different prices BP and Shell charge at the forecourts they own and run. Worryingly, there is sometimes as much as 30p between their high and low prices. We badly need to see an end to this practice as this postcode lottery is extremely unfair on drivers. Those who want to make sure they get the best price should download the free myRAC app and start using its fuel finder feature.
“On a more positive note, it’s good to see the average retailer margin on petrol come down from 10.5p a litre at the start of March to under 8p. While the cause is most likely to be the increase in the wholesale price of petrol, it could also be due to the CMA again raising concerns about higher retailer margins very publicly just last week.”
Motorists looking to save money on their fill-ups should take advantage of the fuel finder feature in the free myRAC app. The app can be downloaded for free from the App Store or Google Play.
Up to nine searches a day can be made over a two, five or 10-mile radius, with each giving the five cheapest prices.
The web page has more information about the average price of petrol and diesel at the big four supermarkets and at motorway services. It also features graphs showing average prices since 2000 as well as a daily financial breakdown of the cost of a litre of petrol and diesel.
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1 UK average pump prices quoted are based on Competition and Markets Authority data from 1-31 March 2024. Wholesale prices, oil price and the value of sterling are based on data from Fuel Prices Online from 1-28 March 2024
