Your petrol car against an electric one: run the numbers

Enter the fuel economy of your current car and the efficiency of the electric car you have in mind. The fuel price is this week’s average and the electricity price the Ofgem cap: change them if yours differ. Nothing you type leaves your browser.

Petrol or diesel car

Fuel

Fuel economy (mpg)

38.7 mpg (7.3 L/100 km): the real-world average of recent petrol cars.

Price per litre (£)

This week’s average price, recorded on 12 October 2026.

Electric car

Model

Efficiency (miles/kWh)

From the car’s or the charger’s display, ideally over several months.

This figure is…what I actually measure, taken as isthe official WLTP figure: 25% real-world use is added

Price per kWh

Miles per year

Average for a private car: 7,100 miles.

Enter a consumption figure and a price for each car: the result appears straight away.

Show the working

Real-world gap added to a WLTP figure (%)

15 to 25% measured on 58,000 cars (TNO 2025); winter and motorway driving widen it.

Share of energy taken from public chargers (%)

Include servicing

Sources: annual mileage, Department for Transport, National Travel Survey 2024 (7,100 miles per car); electricity, Ofgem Energy Price Cap, 1 October to 31 December 2026, direct debit, Great Britain average, no VAT; fuel, weekly road fuel prices from the Department for Energy Security and Net Zero (DESNZ), prices of 12 October 2026; reference consumption, JRC 2025 (on-board meters of 7.7 million petrol cars); real-world gap, TNO 2025 and ICCT 2025; servicing, ADAC (January 2026) and Roole Data (2024). Checked on 5 October 2026.

Calculator by sohpass.com — fuel and electricity prices updated every week. See the full working and the cost model by model.