Diesel pump prices are 20p per litre more than for petrol.

However, according to the RAC, there is little difference in the two fuels’ wholesale prices.

The RAC is urging retailers to cut diesel pump prices to “fairer levels” which reflect costs.

Subsidising petrol

RAC Fuel Watch data shows the average price of diesel was 168p per litre, last week, while the wholesale cost was 121.06p. It means retailers are pocketing more than double the margin on every litre they sell, compared to petrol.

The RAC calculates that if diesel was being sold at a fairer rate drivers would be paying no more than around 155p per litre. This would make the cost of filling an average 55-litre family car £7 less than it is today (£85.25, compared to the current £92.40).

Analysis by the RAC found that retailers are “subsidising” cheaper petrol by taking a margin of 20p on every litre of diesel they sell. Latest Government figures show 17.6 million vehicles licensed in the UK are diesel-powered, including the vast majority of vans. This represents 43% of all vehicles on the road.

Premium prices

“Drivers of the country’s diesel vehicles have every right to feel hard done by,” states  RAC spokesman Simon Williams. “They’re paying a huge premium for the fuel which in no way reflects its lower wholesale cost.

“For nearly a month, the gap between wholesale petrol and diesel prices has been less than 10p a litre and in recent days it has reduced to just 3.5p, ” adds Williams. “Yet average diesel prices at the pumps remain stubbornly high, having fallen by only 2p since the start of February.

“The fact membership-only retailer Costco has been able to cut the average price of a litre of diesel by 4p last week shows what’s possible, but we badly need other fuel retailers to treat drivers of diesel vehicles fairly.”

Driving change

The RAC is calling on retailers to urgently cut the price of diesel to fairer levels, following the lead of membership-only retailer Costco which this week lopped 4p off diesel at its sites across the UK, meaning it is now charging an average of 154.7p – 13p less than the UK average and 11.5p less than the average at the UK’s big four supermarkets.