Why does diesel cost more than petrol?
Diesel costs more than petrol in the UK because the fuel itself costs more to buy on the wholesale market, and retailers have tended to take a bigger margin on it. Tax is not the reason. Both fuels pay exactly the same fuel duty and VAT. Right now the average litre of diesel is 199.2p, against 174.2p for petrol, a difference of 25.0p a litre.
Is fuel duty higher on diesel?
No. Petrol and diesel pay the same main rate of fuel duty, currently 52.95p a litre. VAT at 20% is then charged on the whole price, including the duty. Because VAT is a percentage, a dearer litre pays slightly more VAT in pence, but the rate is the same. For a full breakdown, see our guide to what makes up the price of petrol.
Why is diesel more expensive to buy wholesale?
The UK imports much of its diesel
The UK uses more diesel than its refineries make. Government figures for the first quarter of 2025 showed the UK imported 59% of its diesel. The closures of refining at Grangemouth and Lindsey in 2025 have added to the country's reliance on imported fuel. Imported diesel is priced on international markets, so UK pump prices follow global supply and demand closely.
Global demand for diesel is high
Diesel and the closely related gas oil are used by lorries, buses, farm machinery, ships, construction plant and for heating. That gives diesel a very large market beyond cars. When supply tightens, for example because of conflict, sanctions or refinery outages, diesel tends to feel it first and for longer.
Refineries can only make so much of each fuel
A barrel of crude oil is split into a mix of products. Refiners can shift that mix only so far, and UK refineries have long been geared more towards petrol than diesel. When diesel is in short supply and petrol is not, the price of diesel rises relative to petrol.
Do retailers make more money on diesel?
Often, yes. In its 2023 road fuel market study, the Competition and Markets Authority (CMA) found that increased margins on diesel across all retailers had cost drivers an extra 13p a litre, and that diesel prices had been slow to fall in 2023. The CMA now monitors retail margins regularly and publishes updates on gov.uk.
Has diesel always cost more than petrol?
The gap changes a lot over time. It has been small for long spells and has widened sharply at times of tight global supply. That is why we show the live difference above rather than a fixed figure. You can see today's averages for both fuels on our UK fuel prices page.
Is a diesel car still cheaper to run?
It depends on how far and how you drive. Diesel holds more energy per litre than petrol, and diesel engines are usually more efficient, so a diesel car often goes further on each litre. If the extra miles per gallon outweigh the higher price per litre, a diesel can still cost less per mile.
To check your own case, compare cost per mile. Divide the price per litre by the miles your car does per litre. A car doing 50 mpg covers about 11 miles per litre. A car doing 40 mpg covers about 8.8 miles per litre. Use the real-world figures for the cars you are comparing, not the brochure figures.
Diesel cars tend to suit drivers who cover lots of longer journeys. For mostly short trips, petrol or hybrid cars usually make more sense, partly because many modern diesels have a particulate filter that needs regular longer runs to clean itself.
Find cheaper diesel near you
Diesel prices vary widely between forecourts, so shopping around makes a real difference. Search by postcode to compare diesel prices at every station nearby, last updated at 17:30 on 16 Oct.
Sources
- GOV.UK: Amended fuel duty rates for 2026 to 2027
- GOV.UK: VAT rates
- CMA: plan to help drivers get more competitive fuel prices (2023)
- DESNZ: Digest of UK Energy Statistics 2026, chapter 3
- Live prices: the UK government's Fuel Finder scheme, via Cheapest Fuel. Contains public sector information licensed under the Open Government Licence v3.0.