Driving 100 miles costs £19.78 in a 40 mpg petrol car, £18.11 in a 50 mpg diesel and £7.52 in an electric car charged at home. Those figures use UK average pump prices of 174.07p a litre for petrol and 199.22p for diesel (week of 26 October 2026), and the Ofgem price cap rate of 26.32p per kWh.
100 miles: petrol vs diesel vs electric
Here is what 100 miles costs at current UK average pump prices, across different vehicle efficiencies:
| Vehicle Type | Efficiency | Cost per 100 Miles | Cost per Mile |
|---|---|---|---|
| Petrol, small car | 50 MPG | £15.83 | 15.8p |
| Petrol, average car | 40 MPG | £19.78 | 19.8p |
| Petrol, SUV or older car | 30 MPG | £26.38 | 26.4p |
| Petrol, inefficient | 25 MPG | £31.65 | 31.7p |
| Petrol, large 4x4 | 20 MPG | £39.57 | 39.6p |
| Diesel, average car | 50 MPG | £18.11 | 18.1p |
| Diesel, SUV or van | 35 MPG | £25.88 | 25.9p |
| EV, home charging (price cap) | 3.5 mi/kWh | £7.52 | 7.5p |
| EV, public rapid charger | 3.5 mi/kWh | £22.57 | 22.6p |
Key takeaway: an electric car charged at home costs £7.52 for 100 miles, against £19.78 in a 40 mpg petrol car. An off-peak EV tariff can cut the home figure by more than half. Public rapid charging at around 79p per kWh costs £22.57, more than the petrol car.
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.
UK fuel prices used here
- Petrol: 174.07p per litre, UK average, week of 26 October 2026 (DESNZ weekly road fuel prices)
- Diesel: 199.22p per litre, same week and source
- Electricity at home: 26.32p per kWh, the Ofgem price cap average for 1 October to 31 December 2026
- Public rapid charging: 79p per kWh, Zapmap pay-as-you-go average for 50kW and faster, September 2026
How the calculation works
For petrol and diesel, the formula is straightforward:
Cost = (Distance / MPG) x 4.546 x Price per litre
4.546 converts UK gallons to litres. So for 100 miles at 40 MPG with petrol at 174.07p:
(100 / 40) x 4.546 x 174.07p = £19.78
For 100 miles at 50 MPG with diesel at 199.22p: (100 / 50) x 4.546 x 199.22p = £18.11
For electric vehicles:
Cost = (Distance / Miles per kWh) x Price per kWh
100 miles at 3.5 mi/kWh with electricity at 26.32p: (100 / 3.5) x 26.32p = £7.52
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, or about 1.0p a mile in a 40 mpg car, so 100 miles would cost roughly £1.04 more. Read our guide to the July 2027 rise for the details, or see what the rise adds to your yearly fuel bill.
Annual cost comparison
The average car in England covered 7,100 miles in 2025 (DfT National Travel Survey). Here is the annual fuel cost by vehicle type:
| Vehicle | Annual Fuel Cost | Saving vs Petrol (40 MPG) |
|---|---|---|
| Petrol (40 MPG) | £1,405 | - |
| Diesel (50 MPG) | £1,286 | £118.57 |
| EV (home, price cap) | £533.92 | £870.70 |
| EV (public rapid only) | £1,603 | £-197.95 |
The case for an EV on fuel cost depends on charging at home. A negative saving means it costs more than the 40 mpg petrol car.
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