EV vs petrol running costs are close enough in some situations and far apart in others, and the deciding factor is usually where the electric car charges. This guide compares the two per 100 km, per year and over ten years using a clear set of assumptions, and shows the fuel price at which a petrol car matches an electric one.
In this guide
The assumptions
The numbers below come from the EV vs petrol cost calculator with its default inputs. The driver covers 15,000 km a year. The electric car uses 18 kWh per 100 km measured at the socket. The petrol car burns 6.5 litres per 100 km. Petrol costs 1.75 per litre, home electricity 0.28 per kWh and public charging 0.55 per kWh. The electric car costs 6,000 more to buy.
Cost per 100 km
The electric car's cost depends on the mix of home and public charging.
With 70 percent of charging at home, the blended electricity price is 0.361 per kWh and the electric car costs 6.50 per 100 km. The petrol car costs 11.38. The electric car is cheaper by about 43 percent.
With 30 percent of charging at home, the blended price rises to 0.469 per kWh and the electric car costs 8.44 per 100 km. The gap against petrol narrows to about 26 percent.
Cost per year and over ten years
| Case | EV energy per year | Petrol per year | Saving per year | Payback of 6,000 premium | Ten-year result |
|---|---|---|---|---|---|
| 70 percent home charging | 975 | 1,706 | 732 | 8.2 years | 1,315 |
| 30 percent home charging | 1,266 | 1,706 | 440 | 13.6 years | -1,601 |
The second case is worse over ten years than owning the petrol car. The car and the mileage are identical, and only the charging habit differs. A driver who charges at home most of the time gets most of the benefit, and one who relies on public chargers gets much less.
The fuel price at which petrol breaks even
Divide the electric car's cost per 100 km by the petrol car's consumption to find the price per litre at which the two cost the same. With 70 percent home charging, that is 6.50 ÷ 6.5, or 1.00 per litre. With 30 percent home charging, it is 8.44 ÷ 6.5, or about 1.30. Fuel prices much above those levels favour the electric car on running costs, and prices below them favour petrol.
This number is useful because fuel prices change faster than anything else in the comparison. If you are deciding for the next ten years, ask how far fuel would have to fall for the petrol car to win.
Why the charging mix matters so much
Home electricity carries no margin for a charging network, so it is usually the cheapest source. Public AC chargers cost more per kWh, and rapid DC chargers cost the most. EV Magazine's provider comparison says the cost of charging in Europe can differ by up to 200 percent between providers. Charging at a workplace, at a supermarket with free charging or on a cheap overnight tariff changes the blended price, so enter a figure that reflects your real habits instead of the best case.
What this comparison leaves out
Running costs are only part of the cost of owning a car. A full comparison would include depreciation, insurance, tyres, parking, road tax and any company-car benefit rules in your country. Maintenance usually costs less for an electric car because there is no oil to change and the brakes wear more slowly, though the saving varies and is easy to overstate, so the calculator treats it as an optional input.
Battery health affects what an electric car is worth when you sell it, and the market for used electric cars is still developing. A long ownership period is kinder to the economics, since the premium is spread over more years of savings.
A simple way to decide
Work through these questions.
- Can you charge at home or at work most of the time?
- How many kilometres do you drive a year? The saving per kilometre is the same, so more driving means more saving.
- What is the real price premium of the electric car you are considering, after any grant or tax benefit?
- What fuel price would make you change your mind?
If you can charge cheaply and drive a lot, an electric car usually wins on running costs. If you cannot charge at home and drive little, the premium is hard to recover on energy alone, though other reasons may still apply.
Frequently asked questions
Is an electric car always cheaper to run?
No. With cheap home charging it usually is. With mostly rapid public charging, the energy cost per km can approach that of a petrol car.
How do I compare a diesel car?
Enter the diesel consumption and price in the same fields. Diesel cars use less fuel per km, so the gap is smaller than against petrol.
Do I need to include electricity used for the cabin and battery heating?
Yes, but the consumption figure measured at the socket already includes them if it comes from your own charging data over a few months.