At the UK average pump price of 174.07p a litre (GOV.UK, week of 26 October 2026), 100 miles of petrol costs between £15.83 and £39.57. The exact figure depends on your car's mpg.
100 miles petrol cost by MPG
Petrol pump price: 174.07p 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 hatchback | 50 | £15.83 | 15.8p |
| Modern small car | 45 | £17.59 | 17.6p |
| Average saloon | 40 | £19.78 | 19.8p |
| Family SUV | 35 | £22.61 | 22.6p |
| Older car / SUV | 30 | £26.38 | 26.4p |
| Older / inefficient | 25 | £31.65 | 31.7p |
| Large 4x4 / V6+ | 20 | £39.57 | 39.6p |
Key takeaway: A typical 40 MPG saloon costs £19.78 for 100 miles at the current UK average petrol price. A 20 MPG large 4x4 doubles that to £39.57. Over a year at the average 7,100 miles (DfT National Travel Survey, England, 2025) that is £1,405 against £2,809.
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 is quoted in imperial, not US, gallons:
Cost = (Distance / MPG) x 4.546 x Price per litre
For 100 miles at 50 MPG with petrol at 174.07p:
(100 / 50) x 4.546 = 9.09 litres, and 9.09 x 174.07p = £15.83
For 100 miles at 40 MPG with petrol at 174.07p:
(100 / 40) x 4.546 = 11.37 litres, and 11.37 x 174.07p = £19.78
For 100 miles at 30 MPG with petrol at 174.07p:
(100 / 30) x 4.546 = 15.15 litres, and 15.15 x 174.07p = £26.38
How much petrol does 100 miles use?
Working in litres rather than cost:
| MPG | Imperial Gallons Used | Litres Used |
|---|---|---|
| 50 | 2.0 | 9.1 L |
| 40 | 2.5 | 11.4 L |
| 30 | 3.3 | 15.2 L |
| 25 | 4.0 | 18.2 L |
| 20 | 5.0 | 22.7 L |
Real-world vs manufacturer MPG
Manufacturer MPG figures are measured under controlled WLTP test conditions. Real-world MPG is typically 10-20% lower because of actual traffic, weather, A/C use, motorway speeds and tyre pressures. If your car is rated 50 MPG WLTP, plan for 40-45 MPG in everyday driving. The 100 mile cost in the table above moves accordingly.
Petrol vs diesel vs EV for 100 miles
Comparing petrol against the alternatives at typical efficiencies:
| Vehicle | Efficiency | Cost for 100 Miles |
|---|---|---|
| Petrol hatch | 50 MPG | £15.83 |
| Petrol saloon | 40 MPG | £19.78 |
| Diesel saloon | 50 MPG | £18.11 |
| Diesel SUV | 40 MPG | £22.64 |
| EV (home, Ofgem price cap rate) | 3.5 mi/kWh | £7.52 |
| EV (public rapid charger) | 3.5 mi/kWh | £22.57 |
At the same mpg, petrol is cheaper than diesel because diesel costs 25.15p a litre more: £15.83 against £18.11 at 50 mpg. An electric car charged at home at the Ofgem price cap rate of 26.32p per kWh costs £7.52, and an off-peak EV tariff can cut that by more than half. Public rapid charging at around 79p per kWh (Zapmap, September 2026) costs £22.57, more than the petrol car.
Annual Petrol Cost (7,100 Miles)
The average car in England covered 7,100 miles in 2025 (DfT National Travel Survey, table NTS0901). At 174.07p per litre:
| MPG | Annual Petrol Cost |
|---|---|
| 50 MPG | £1,124 |
| 40 MPG | £1,405 |
| 30 MPG | £1,873 |
| 20 MPG | £2,809 |
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 40 mpg petrol car would cost about £1.04 more. Read our guide to the July 2027 rise for the details, or put your own mileage and mpg into the fuel duty rise calculator.
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