Live data from 7,444 UK stations via the UK Gov Fuel Finder API, updated every 15 minutes
The scale of the gap
Before the Middle East conflict began on 28 February, diesel cost around 142p per litre and petrol around 133p — a gap of less than 10p. That's fairly normal. Over the past two decades, diesel has typically cost only around 5p per litre more than petrol.
Today, the gap has blown out to over 30p per litre — smashing the previous record of around 24p set during the 2022 Ukraine crisis. Diesel has jumped by roughly 40p per litre in little over a month, while petrol has risen by around 20p. In real terms, that means filling a 55-litre diesel car now costs around £21 more than it did in late February. A petrol car costs roughly £11 more.
Cost of a full tank today: A 55-litre petrol fill-up now costs around £86. A 55-litre diesel fill-up costs around £103. That's a difference of roughly £17 per tank — and the gap is still widening.
Why has diesel been hit so much harder?
Both fuels come from crude oil, but diesel is being affected by a combination of factors that don't apply to petrol in the same way.
1. The UK imports most of its diesel
This is the biggest single reason. The UK only refines around half of the diesel it needs domestically. The rest is imported, mainly from the Netherlands, the US and other international markets.
Petrol is different — the UK produces enough petrol domestically to meet demand. So when global supply chains are disrupted, diesel is far more exposed to international price spikes than petrol is.
The Strait of Hormuz, through which roughly 20% of global oil trade passes, has been disrupted by the ongoing Middle East conflict. While less than 1% of the UK's oil comes directly from the Persian Gulf, global markets are highly interconnected. Disruption anywhere in the supply chain pushes up wholesale prices for traded fuels — and diesel, as a heavily imported product, feels this more acutely.
2. Diesel has wider demand beyond cars
Petrol is almost exclusively a road fuel. Diesel is not. It powers lorries, delivery vans, buses, trains, agricultural machinery, construction equipment and some heating systems. When supply tightens, more industries are competing for the same fuel, pushing the price up faster.
Diesel is also chemically similar to heating oil. In colder months, demand for heating oil increases competition for the same distillate products, adding further seasonal price pressure that petrol doesn't face.
3. Biodiesel blending margins have collapsed
Diesel sold at UK pumps typically contains up to 7% biodiesel (known as FAME). Suppliers use this blending to help manage costs and meet environmental obligations. Earlier in the year, the biodiesel component was worth around 8p per litre in margin support.
However, FAME prices have stayed largely flat while mineral diesel has surged. The blending benefit has collapsed to less than 1p per litre. This has pushed suppliers to buy more fuel on expensive spot markets rather than through cheaper contracts — adding further upward pressure on diesel specifically.
4. Wholesale costs haven't fully passed through yet
As striking as current diesel prices are, the wholesale increase has actually been even larger. Wholesale diesel has risen by over 41p per litre since late February — a 74% increase — while the pump price has risen by around 39p. That means retailer margins are currently being squeezed, and some analysts expect a further 10–15p of increases may still need to pass through to restore normal margins.
Prices may still rise further. Industry analysis suggests diesel could reach the 190–200p range if the Middle East situation remains unresolved. Some London forecourts have already been reported above 200p per litre.
What about petrol — why has it risen less?
Petrol has still risen significantly — by around 20p per litre — but the increase has been roughly half that of diesel. The main reasons are straightforward:
- Domestic supply: The UK produces enough petrol to meet its own demand, so it's less exposed to global supply disruption.
- Narrower demand: Petrol is almost entirely used for cars. It doesn't face the same competing demand from industry, transport and heating that diesel does.
- Wholesale increase was smaller: Wholesale petrol has risen by around 20p per litre compared to over 41p for diesel.
How does this compare to previous fuel crises?
During the 2022 Ukraine crisis, the diesel-petrol gap reached a then-record of around 24p in November 2022. Today it has exceeded 30p. However, the absolute prices are still below the all-time highs of July 2022, when petrol peaked at 191.6p and diesel at 199.2p.
What makes 2026 different is the speed of the increase. The RAC has described March 2026 as "truly unprecedented" — fuel prices have never risen this fast in a single month. Diesel's 40p increase in March alone is 18p more than the previous monthly record.
The knock-on effects beyond the pump
Because diesel powers so much of the UK's supply chain — from supermarket deliveries to construction — higher diesel prices feed through into the wider economy. Haulage costs rise, which can push up the price of food, building materials and consumer goods. The Road Haulage Association has warned that these costs are already being felt across the supply chain and will ultimately be passed on to households.
What can drivers do?
You can't control the global oil market, but you can control where and how you buy fuel:
- Compare prices before filling up — prices can vary by 20p or more per litre between nearby stations. Even a short detour can save several pounds per tank.
- Favour supermarket forecourts — they're typically 5–10p per litre cheaper than branded stations, saving £2.75–£5.50 on a 55-litre tank.
- Avoid motorway service stations — they often charge 15–20p more per litre than nearby town forecourts.
- Drive more smoothly — avoiding harsh acceleration and braking can improve fuel efficiency by up to 10%, saving around £10 per tank at current diesel prices.
- Check tyre pressures — underinflated tyres increase fuel consumption. Correct pressures can improve economy by 2–3%.
Use our free price comparison tool to find the cheapest petrol and diesel near you. With prices this volatile, checking before every fill-up makes a bigger difference than ever.
What happens next?
The outlook depends heavily on how the Middle East situation develops. If tensions ease and shipping through the Strait of Hormuz returns to normal, wholesale prices could settle — and the diesel-petrol gap would gradually narrow. But if disruption continues or escalates, prices could rise further, and the gap could persist well into summer.
On top of global factors, the UK's planned fuel duty increases from September 2026 will add further pressure. Duty is set to rise by 1p per litre in September, 2p in December and 2p in March 2027 — returning to 57.95p per litre. With VAT on top, that's an extra 6p per litre at the pump by March 2027.
There are growing calls from motoring groups and opposition parties to delay these increases given the current crisis, but the government has so far only said it keeps fuel duty "under review."
Bottom line: Diesel is more expensive than petrol right now because the UK imports much of its diesel, it faces competing demand from industry and logistics, and biodiesel blending margins have collapsed. These structural factors mean the gap is likely to persist even after the immediate crisis eases.