Everyday
Petrol vs electric running cost
How do estimated energy costs compare for the same annual mileage in a petrol car and an EV?
Switching from petrol to electric is often sold as a running-cost story: electricity per mile versus petrol per mile. That comparison is real, and it is also incomplete. Purchase price, insurance, depreciation, servicing, tyres, vehicle tax and where you charge — a home unit rate versus a public rapid — can dominate the lifetime arithmetic. This experiment starts with the narrow question, estimated energy cost for a mileage, efficiency and prices you provide, and keeps purchase and other standing costs off unless you switch them on. HMRC advisory fuel rates, DESNZ pump prices and Ofgem electricity unit rates are useful context for the defaults; they are not your bill. Compare the estimated difference in running cost. It is not a verdict on which car to buy.
Change this
Results update as you move the controls.
UK miles per imperial gallon.
Usually a home unit rate.
Insurance, tax, a depreciation or finance figure — off by default.
Your result
£791
estimated petrol energy cost above EV
Energy only — purchase, insurance and depreciation are excluded.
- Petrol energy cost
- £1,340
- EV energy cost
- £549
- Petrol pence per mile
- 16.7p
- EV pence per mile
- 6.9p
957 litres at 140p/L.
2,286 kWh at 24p/kWh.
What does that mean?
For 8,000 miles, petrol energy is estimated at £1,340 and EV electricity at £549. Compare the estimated difference in running cost (£791). Purchase, insurance, depreciation and public charging are excluded unless you switch them on.
At a glance
- Petrol£1,340
- Electric£549
Compare
| Petrol energy / year | £1,340 | |
|---|---|---|
| EV energy / year | £549 | |
| Standing costs | Excluded | Toggle on to add insurance, tax or depreciation. |
Compare scenarios
Energy cost is not total cost of ownership
Energy Saving Trust’s own total-cost examples put lease or purchase, servicing and vehicle tax beside fuel. A cheap-to-run EV can still be the dearer car once you pay for it. The optional fixed-cost toggle exists so you can add annual insurance, tax and a rough depreciation or finance figure without pretending those numbers came from the mpg slider.
Efficiency figures are yours
WLTP mpg and miles per kWh are test-cycle numbers. Real cold-weather EV range and urban petrol consumption diverge from the brochure. HMRC advisory fuel rates are built from typical mpg bands and DESNZ pump prices; they are a cross-check, not a substitute for the mpg you observe on a tank.
Where you charge changes the electricity line
The default 24p/kWh sits near recent average unit rates discussed by Ofgem and Energy Saving Trust fleet tools. An off-peak EV tariff can be much lower; a public rapid charger can be much higher, occasionally above petrol on a pence-per-mile basis. Put the rate you actually pay on the slider rather than a headline cap.
How we calculated this
Petrol litres per year = annual miles ÷ mpg × 4.54609 (UK gallon). Petrol cost = litres × pence per litre ÷ 100. EV kWh per year = annual miles ÷ miles per kWh. Electricity cost = kWh × pence per kWh ÷ 100. If “include standing costs” is on, the annual petrol and EV fixed amounts you enter are added. Purchase price, public versus home charging mix, tyres and depreciation are otherwise excluded. This experiment provides estimates for educational purposes and is not financial advice. Actual results vary depending on rates, fees, taxes, inflation and individual circumstances.
Go further
A curated rabbit hole from this question. Each link is a real experiment, not a random suggestion.
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