Why Is Diesel More Expensive Than Petrol in the UK?

For years diesel was the cheaper fuel. In late October 2026 it is the other way round: the average price of diesel was about 199.22p a litre against 174.07p for petrol, a gap of roughly 25p. A year earlier the gap was only around 8p.

The tax is the same, the price is not

Fuel duty is 52.95p per litre on both fuels. So the 25p difference is not duty. It comes from the cost of the fuel itself, and VAT at 20% then adds a little more on top of the higher price.

What has pushed diesel up

Reports on the 2026 price rise point to a few causes:

• Tight global supply of refined diesel. It is not just crude oil that has become dearer. The refined product has been in particularly short supply worldwide.
• The UK imports a large share of its diesel. That makes UK pump prices sensitive to what is happening in international markets.
• Crude oil prices. Shipping disruption in the Middle East has been reported as a factor in oil topping $100 a barrel in late September.

These are the drivers cited by motoring and market commentators, and they can change quickly. For the general picture see how oil prices reach the petrol pump.

Does diesel still make sense for your car?

A diesel engine uses less fuel per mile. The question is whether the saving covers the dearer fuel. The break-even is easy to calculate:

Diesel price ÷ petrol price = 199.22 ÷ 174.07 = 1.14

So a diesel car needs to be about 14% more efficient than a similar petrol one to cost the same per mile. If your diesel does 50 mpg and the petrol equivalent does 40 mpg, diesel is 25% better and still wins. If the gap is only 10%, petrol is now cheaper to run.

Here is what that looks like in practice:

Don't forget the other factors

Running cost is not only fuel. Diesel cars often cost more to buy, and some older diesels face extra charges in clean-air zones. If you do few miles, the engine's fuel saving matters less.

How to pay less for diesel today

Diesel prices vary a lot between stations. In our database the cheapest diesel (B7) we found was around 176p while the dearest was above 232p. Supermarkets tend to be cheaper on average, and motorway services much dearer. Read are supermarket petrol stations cheaper? and how much more does motorway fuel cost?.

Compare diesel prices near you and let the ranking include the cost of getting there.