At April 2026 UK pump prices, 100 miles of petrol costs between £14.37 and £35.91. The exact figure depends on your car's MPG. Petrol is currently 158p per litre, broadly stable through the first half of 2026 after the March price spike that mainly affected diesel.
100 Miles Petrol Cost by MPG (April 2026)
Petrol pump price: 158p per litre. Imperial gallon conversion: 4.546 litres per gallon.
| Vehicle | MPG | Cost for 100 Miles | Cost per Mile |
|---|---|---|---|
| Efficient hatchback | 50 | £14.37 | 14.4p |
| Modern small car | 45 | £15.97 | 16.0p |
| Average saloon | 40 | £17.96 | 18.0p |
| Family SUV | 35 | £20.53 | 20.5p |
| Older car / SUV | 30 | £23.94 | 23.9p |
| Older / inefficient | 25 | £28.73 | 28.7p |
| Large 4x4 / V6+ | 20 | £35.91 | 35.9p |
Key takeaway: A typical 40 MPG saloon costs £17.96 for 100 miles at current UK petrol prices. Doubling that to a 20 MPG large 4x4 doubles the cost to £35.91. Across an average 7,400 mile year that gap is £1,328.
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 158p:
(100 / 50) x 4.546 x 1.58 = £14.37
For 100 miles at 40 MPG with petrol at 158p:
(100 / 40) x 4.546 x 1.58 = £17.96
For 100 miles at 30 MPG with petrol at 158p:
(100 / 30) x 4.546 x 1.58 = £23.94
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 | £14.37 |
| Petrol saloon | 40 MPG | £17.96 |
| Diesel saloon | 50 MPG | £17.37 |
| Diesel SUV | 40 MPG | £21.71 |
| EV (home, standard tariff) | 3.5 mi/kWh | £6.86 |
| EV (home, off-peak tariff) | 3.5 mi/kWh | £2.86 |
| EV (public rapid charger) | 3.5 mi/kWh | £14.29 |
Petrol at 50 MPG is now the cheapest combustion option. Diesel at 50 MPG is £3 more for 100 miles thanks to the March 2026 diesel spike. An EV charged at home on an off-peak tariff is the clear winner at £2.86, roughly one-fifth of an equivalent petrol car.
Annual Petrol Cost (7,400 Miles)
The average UK driver covers 7,400 miles per year. At 158p per litre:
| MPG | Annual Petrol Cost |
|---|---|
| 50 MPG | £1,063 |
| 40 MPG | £1,329 |
| 30 MPG | £1,772 |
| 20 MPG | £2,657 |
Fuel Duty Changes Coming
The current 5p per litre fuel duty cut ends 31 August 2026. After that, duty rises in three stages: +1p in September, +2p in December, +2p in March 2027. By March 2027 a 100 mile journey in a 40 MPG petrol car will cost roughly 57p more than today. Read our fuel duty changes guide for the full schedule.
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