Diesel on UK forecourts averages 191.5p per litre this week; unleaded, 158.3p. A 33p gap between two fuels that, ten years ago, often sat within 2-3p of each other. If you own a diesel van, a diesel commuter car, or run a small fleet, you’re paying roughly £18 more per 55-litre tank than a petrol driver — and the gap has been widening, not closing, all year.
The historical gap
Diesel has typically been slightly more expensive than petrol in the UK for a simple reason: duty has been the same on both since 2001, and wholesale diesel is a bit more expensive to refine per litre. The usual gap sits at 2-6p/L.
A 33p gap is not usual. The last time diesel was this far ahead of unleaded was the first half of 2022, during the Ukraine-Russia refined-product disruption. The comparison is apt — both episodes involve a sudden loss of diesel imports from a specific region that European refineries can’t fully replace.
Why diesel is taking the brunt in 2026
Three structural reasons, all pulling the same way:
- European refineries run a diesel deficit. A typical European refinery’s product mix produces more petrol than the local market consumes, and less diesel. The shortfall is made up by imports — historically from the Persian Gulf and Russia. Both supply routes are currently impaired (Russia since 2022 sanctions; the Gulf since the 28 February strait closure). Every litre of diesel you burn is competing with fewer import barrels than it was in January.
- Refinery yield is largely fixed. When refiners see diesel cracks widening, they tweak operations towards more diesel — but the wiggle room is narrow. The physical chemistry of cracking crude into products means you can’t produce dramatically more diesel by cutting gasoline; the yields are set by the refinery’s configuration. Europe would need new hydrocracker capacity to close the gap, and that takes years.
- Heating oil shares the supply chain. In the UK, Ireland, and much of northern Europe, heating oil (red diesel off-road, kerosene domestic) comes from the same refinery streams as road diesel. A cold spring kept heating demand elevated into April 2026 — right as the Middle East shock hit. Diesel stocks drained faster than petrol.
Why not petrol
Petrol hasn’t been immune — up about 20p/L since 28 February — but the impact is softer for the mirror reasons:
- Europe is structurally long on gasoline — refineries produce a surplus that Europe exports (mainly to the US East Coast). A global supply shock eats into export volume before it eats into domestic availability.
- The US is a gasoline-heavy consumer (more petrol cars, bigger engines) and absorbs European gasoline exports even at higher prices. European stocks stay relatively full.
- Heating oil doesn’t overlap with gasoline supply — so a cold spring tightens diesel without touching petrol.
What it means for diesel drivers
Three practical points, none of them fun:
- The gap won’t close until the strait reopens. Unless and until Gulf diesel exports normalise, the 30p+ gap is the new floor. Analysts at JP Morgan and the EIA see Q2 2026 as the peak; we should be below 25p by autumn on current base cases.
- Per-mile economics may have flipped. A diesel car typically does 20-30% more miles per litre than a petrol equivalent, so a 20p premium traditionally still left diesel the cheaper choice per mile. At 33p+, the break-even point moves — for some smaller diesels against efficient hybrids, diesel is now more expensive per mile than petrol.
- Fleet operators should be hedging or switching. If you run ten vans and do 15,000 miles each, the 33p gap is costing around £8,000 a year versus a petrol-equivalent fleet. Not sufficient to swap tomorrow, but sufficient to recalculate the next lease cycle.
How to mitigate
The same levers that always apply, sharpened by a wider price spread:
- Comparing is worth more now. The station-to-station gap on diesel specifically is running 12-18p within a five-mile radius — higher than normal, because retailer lag differs more when wholesale is volatile.
- Loyalty cards help disproportionately. 2-3p/L of loyalty discount is a larger percentage saving against a base of 191p than it is against a base of 158p. See our loyalty card ranking for which scheme to prioritise.
- Track the real per-mile number. The sticker on the tank matters less than pence per mile across your actual driving. Our Member-tier per-mile view reconciles pump prices with your vehicle’s MPG so the comparison is apples-to-apples.
See the cheapest diesel in the UK right now →
Or compare diesel prices near you by postcode →