Petrol prices rise while diesel falls, widening questions over pump price gap
- Perry Richardson
- 2 hours ago
- 3 min read
UK drivers experienced contrasting fuel price trends in May, with petrol costs increasing while diesel became cheaper, according to the latest RAC Fuel Watch analysis.
The average price of unleaded petrol rose by 2.4p per litre during the month, climbing from 157p to 159.4p. For motorists filling a typical 55-litre family car, this added £1.32 to the cost of a full tank, taking it from £86.36 to £87.68. In contrast, diesel prices fell by 4.5p per litre from 188.4p to 183.9p, reducing the cost of a 55-litre fill-up by £2.50 to £101.13.
The differing movements in price were driven by wholesale market trends. RAC data shows the wholesale cost of petrol increased during the middle of May, while diesel wholesale prices continued to decline. By 14 May, a litre of delivered petrol cost retailers 123.5p before VAT and retailer margins, compared with 133.3p for diesel. This reduced the wholesale price gap between the two fuels to around 10p per litre at one stage.
Despite the narrowing wholesale difference, the gap between average UK pump prices remains significantly wider. At the end of May, diesel was still around 25p per litre more expensive than petrol at forecourts across the UK, a disparity likely to remain under scrutiny from both motorists and industry observers.
Supermarkets continued to offer lower petrol prices than the national average. Unleaded petrol at the major supermarket chains averaged 155.6p per litre at the end of May, around 4p cheaper than the UK-wide average. Petrol prices at supermarkets increased by 1.4p during the month, notably less than the national increase of 2.4p.
Diesel at supermarkets averaged 182.5p per litre at the end of May, around 1.4p below the UK average. Prices fell by almost 4p during the month, broadly reflecting the wider decline seen across the diesel market. For fleet operators, taxi drivers and other high-mileage users, the continued reduction in diesel costs provided some relief from elevated operating expenses.
RAC head of policy Simon Williams said: “May was a better month for drivers of diesel vehicles than it was for petrol. Those relying on unleaded had to endure yet another rise at the pumps, while those who use diesel saw a welcome 4.5p reduction.
“It’s really quite unusual to see the price of one fuel go up and the other come down. This was brought about by the wholesale cost of unleaded rising due to higher demand in the United States. This coincided with a drop in demand for heating oil in western Europe which is refined from the same part of the barrel as diesel.
“The last week of the month also saw the price of Brent crude drop below $100 which ought to prove to be good news for drivers as it should lead to far lower prices. The wholesale price of diesel has been far lower than its peak for some time which we had hoped would yield far bigger forecourt reductions. Petrol, however, could have risen further than it did, so it might have been the case that retailers decided to keep the price of unleaded down at the expense of greater diesel reductions.
“On 1 June, the Competition and Markets Authority published its latest report on the road fuel market which found retailers hadn’t altered their pricing strategies during the war but these were largely passive and lacking in competition. It also said that retailer margins remained at historically high levels and that it would be concerned if current high retail prices persist given wholesale prices are no longer increasing.
“We hope its next report shows that drivers have been treated fairly by retailers reducing their pump prices in line with the fall in wholesale costs.”
