If you drive a diesel car, you will already have noticed that filling up has become significantly more painful than it is for petrol drivers. The average price of diesel at UK pumps has hit around 178p per litre, compared to roughly 150p for petrol. That is a gap of nearly 28p per litre — the widest it has been in years, and it is costing diesel drivers a significant amount more every time they fill up.
Why has diesel been hit harder than petrol?
Both fuels come from the same source — crude oil — but they are refined differently, and diesel has a particular vulnerability to the current crisis that petrol does not share to the same degree.
The UK refines relatively little of its own diesel. We import a large proportion from abroad, and those import routes have been severely disrupted by the conflict in the Middle East and the near-shutdown of shipping through the Strait of Hormuz. UK diesel wholesale spot prices increased by more than 37% in a single week after the outbreak of the conflict — a far sharper jump than petrol saw.
There is also a longer-term structural issue. The UK's diesel refining capacity has been declining for years as demand for petrol cars fell and refineries adapted. When supply is tight and imports are disrupted, that lack of domestic capacity feeds straight through to the price at the pump.
The rocket and feather problem
Diesel drivers have faced another frustration for years: prices go up quickly when wholesale costs rise, but come down slowly when they fall. There is clear evidence of rocket and feather pricing for diesel, which has been used as a strategy to increase margin in a manner that is less visible to consumers than increasing prices. The Competition and Markets Authority has previously investigated this practice, and ministers have again asked it to keep the fuel market under review during the current crisis.
Is the gap likely to narrow?
In the short term, probably not. The factors driving diesel higher — import disruption, refining capacity constraints, and the global oil price shock — are all still in play. The average pump price for diesel has climbed above 161p for the first time since November 2023, and data suggests it is on course to hit 170p soon — and some forecasts suggest it could go higher still if the Strait of Hormuz remains disrupted.
There is also a looming tax change to be aware of. The 5p per litre fuel duty cut, first introduced in 2022, is due to be phased out from September 2026 and removed entirely by March 2027, which would push both petrol and diesel prices higher still.
What can diesel drivers do right now?
You cannot change what fuel your car runs on, but you can control what you pay per litre. With a 27p gap between the cheapest and most expensive diesel stations in many areas, where you fill up matters enormously.
- Supermarkets are consistently the cheapest for diesel. Asda, Tesco, Sainsbury's and Morrisons typically price diesel significantly below motorway services and branded forecourts. Use the Diesel B7 filter on Save at the Pump to find your nearest supermarket with the cheapest price.
- Avoid motorway services. Motorway service stations are charging around 182p per litre for diesel — that is around 4-5p above the national average, adding over £2 to every fill-up for no reason other than convenience.
- Use our Worth the Drive Calculator. Enter your MPG and tank size, select Diesel B7, and we will tell you whether it is worth driving to a cheaper station factoring in the fuel you use getting there.
- Fill up earlier in the week. Prices at many stations tend to creep up on Thursdays and Fridays ahead of weekend demand.
- Drive more efficiently. Smooth acceleration, gentle braking, and keeping your speed steady can improve fuel economy by 10-15%, effectively reducing the real cost per mile even at current prices.
The diesel premium is likely here to stay for the foreseeable future. The best response is to make sure you are always paying as little as possible for the diesel you do use — and that starts with knowing what the cheapest stations near you are charging right now.