The RAC has warned all UK drivers who own a diesel car that they'll still end up paying more while filling up - even though they technically shouldn't have to.
New data has revealed that diesel costs around 17.5p more per litre than petrol at fuel stations despite both fuels selling for around 114.5p on the wholesale market.
According to RAC Fuel Watch, the average price of petrol stands at 146.63p while diesel is 164.26p. But in terms of wholesale, they're very much the same - and on two days last week, diesel actually cost even less than petrol.
Since the start of March the average weekly wholesale price of diesel has fallen 5p a litre while unleaded has remained the same (diesel – 119p to 114.5p; petrol 114.6p to 114.7p).
The RAC has described the situation as 'absolutely shocking', especially since the wholesale prices are 'virtually identical'.
At the start 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, RAC has said.
Fuel spokesman Simon Williams said: "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.
"Sadly, this seems unlikely given current retailer behaviour. Instead, the big four supermarkets, which dominate UK fuel retailing, are charging an outrageous of 162p a litre on average."
He's said that supermarkets should be doing more to bring their prices down - especially in the midst of the cost of living crisis which is already piling pressure on families.
The only retailer that seems to be bucking this trend at the moment is Costco, the RAC has said, which is charging just under 150p a litre for diesel at the moment. However, you need to be a member in order to fill up your car here.
Simon added: "We are also seeing many independent retailers charging far less than their supermarket rivals which is a sign of how much fuel retailing has changed. This would have been pretty unusual several years ago but is now rapidly becoming the norm.
"If smaller retailers can afford to make ends meet with lower margins and smaller sales volumes, then what excuse can the supermarkets possibly have for keeping their diesel prices so high?
"We hope the Competition and Markets Authority, which is currently reviewing the road fuel market in the UK, is keeping a watchful eye on this pricing behaviour as we believe it’s against the interests of diesel drivers up and down the country."
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