The UK average price of a litre of diesel is still 17p higher than that of petrol, despite retailers buying the fuel for roughly the same amount. That’s the conclusion drawn from data produced by the RAC’s Fuel Watch initiative, which tracks fuel prices across the UK.

According to the scheme, the average litre of unleaded petrol costs 146.63p in the UK, whereas the average litre of diesel comes in at 164.26p. However, the wholesale price – the amount retailers pay to stock the fuel – is almost identical at 114.5p per litre for diesel and 114.7p per litre for petrol.

Since March, the RAC data shows the wholesale price of diesel has fallen by 5p per litre while the petrol wholesale price has remained the same. As a result, the motoring organisation has branded the disparity in price as “shocking” and says average diesel prices should have fallen below 150p per litre.

Pumping diesel fuel at petrol station

The company has pointed the finger at supermarkets primarily, saying they have had “plenty of time” to pass on lower prices, but remain “resolute” in their refusal to do so. In the midst of a cost-of-living crisis, the RAC said the decision to keep prices high was “scandalous”, although the company praised Costco for dropping diesel prices to around 150p per litre.

Fuel retailers are currently under investigation from the Competition and Markets Authority (CMA) over allegations of so-called rocket-and-feather pricing, with prices shooting up when the cost of oil increases, but falling more slowly when costs decrease. The RAC says it hopes the CMA is keeping a “watchful eye on this pricing behaviour”.

“The forecourt price disparity between petrol and diesel across the UK is absolutely shocking given their wholesale prices are now virtually identical,” said RAC fuel spokesperson Simon Williams. “At the beginning of March wholesale diesel was only 6p more expensive than petrol yet there was a 20p-a-litre gap between both fuels on the forecourt. Now the two fuels are identical on the wholesale market, and there’s still more than 17p difference at the pump.

“For retailers to be taking a margin of nearly 20p a litre on average throughout March, compared to the long-term average of 7p, is devastating for every driver and business that relies on diesel. The price of a litre of diesel should have already come down to around 152p, and now the wholesale price is the same as petrol at 114p we really should soon be seeing forecourts displaying prices of 147p.”

Car refueling at the petrol station