At the UK average pump price of 199.22p a litre (GOV.UK, week of 26 October 2026), driving 100 miles in a diesel car costs between £15.09 and £30.19. The exact figure depends on your vehicle's mpg. Diesel was around 141p a litre in February 2026; the March supply disruption pushed it past 190p and it has stayed high since.
100 miles diesel cost by MPG
Diesel pump price: 199.22p per litre, the UK average for the week of 26 October 2026 (DESNZ weekly road fuel prices). Imperial gallon conversion: 4.546 litres per gallon.
| Vehicle | MPG | Cost for 100 Miles | Cost per Mile |
|---|---|---|---|
| Efficient diesel hatch | 60 | £15.09 | 15.1p |
| Modern saloon | 55 | £16.47 | 16.5p |
| Saloon / estate | 50 | £18.11 | 18.1p |
| Mid-size SUV | 45 | £20.13 | 20.1p |
| Large SUV / pickup | 40 | £22.64 | 22.6p |
| Van / older diesel | 35 | £25.88 | 25.9p |
| Heavy van / 4x4 | 30 | £30.19 | 30.2p |
Key takeaway: A modern 50 MPG diesel saloon costs £18.11 for 100 miles at the current UK average price. The same journey in a 30 MPG van costs £30.19. Over a year at the average 7,100 miles (DfT National Travel Survey, England, 2025) that is £1,286 against £2,143.
This guide gives an estimate, not financial advice. For decisions about your own money, check with a qualified adviser or HMRC.
The Budget changes were announced on 28 October 2026. Some details are still being confirmed and may change before they take effect, and we update this page as they do.
How the calculation works
The formula uses imperial gallons because UK MPG figures are quoted in imperial, not US, gallons:
Cost = (Distance / MPG) x 4.546 x Price per litre
For 100 miles at 50 MPG with diesel at 199.22p:
(100 / 50) x 4.546 = 9.09 litres, and 9.09 x 199.22p = £18.11
For 100 miles at 40 MPG with diesel at 199.22p:
(100 / 40) x 4.546 = 11.37 litres, and 11.37 x 199.22p = £22.64
Why diesel is more expensive than petrol per litre
Diesel currently sits 25.15p a litre above petrol in the UK (199.22p against 174.07p). Diesel has usually cost a few pence more than petrol here; the gap was about 10p in February 2026. It widened in March 2026 when the conflict with Iran disrupted oil supply through the Strait of Hormuz, and because the UK imports much of its diesel, diesel rose faster than petrol. The gap has not closed since.
Diesel engines are still 15-20% more efficient per litre than equivalent petrol engines, which is what makes diesel competitive on cost per mile despite the higher pump price. But the per-litre premium has narrowed diesel's per-mile advantage to almost nothing for drivers swapping like-for-like.
Diesel vs petrol vs EV for 100 miles
Comparing diesel against the alternatives at typical efficiencies:
| Vehicle | Efficiency | Cost for 100 Miles |
|---|---|---|
| Diesel saloon | 50 MPG | £18.11 |
| Petrol saloon | 50 MPG | £15.83 |
| Petrol average | 40 MPG | £19.78 |
| EV (home, Ofgem price cap rate) | 3.5 mi/kWh | £7.52 |
| EV (public rapid charger) | 3.5 mi/kWh | £22.57 |
An electric car charged at home at the Ofgem price cap rate of 26.32p per kWh costs £7.52 for 100 miles, and an off-peak EV tariff can cut that by more than half. A diesel only beats petrol when the diesel is clearly more efficient: a 50 MPG diesel (£18.11) against a 40 MPG petrol (£19.78) is cheaper per mile; a 40 MPG diesel (£22.64) against a 50 MPG petrol (£15.83) is not.
Annual Diesel Cost (7,100 Miles)
The average car in England covered 7,100 miles in 2025 (DfT National Travel Survey, table NTS0901). At 199.22p per litre:
| MPG | Annual Diesel Cost |
|---|---|
| 60 MPG | £1,072 |
| 50 MPG | £1,286 |
| 40 MPG | £1,608 |
| 30 MPG | £2,143 |
Fuel Duty Rises on 1 July 2027
Fuel duty stays at 52.95p a litre until 30 June 2027 after the Budget on 28 October 2026, which cancelled the rises planned for January and March 2027. From 1 July 2027 it is set to be 60.59p. With VAT that adds 9.17p a litre, so 100 miles in a 50 mpg diesel car would cost about £0.83 more. Read our guide to the July 2027 rise for the details, or work out the rise for your own car.
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