The tariff decides everything
If you charge your car at home using a cheap overnight EV tariff, running an electric car costs much less per mile than petrol. On off-peak home rates, a typical EV costs just a few pence per mile for energy, while a 40 mpg petrol car at current pump prices costs several times more.
However, if you use public rapid chargers, the situation changes. Rapid chargers are the most expensive way to charge an EV, and the cost per mile can get close to that of petrol. This is why we do not give a single 'average cost' figure, as it would not be accurate for most people.
Cost per mile: electric car vs petrol
On a cheap overnight EV tariff at around 7p/kWh, a typical electric car costs roughly 2 to 3p per mile for energy. A 40 mpg petrol car at current pump prices of around 140p per litre costs about 16p per mile. That's a five-to-one difference in the best case.
On a standard electricity rate at 24.50p/kWh, the EV cost rises to about 7 to 8p per mile, still half the cost of petrol. On public rapid chargers at around 79p/kWh, the EV costs over 20p per mile, at which point it's not far from petrol and the financial case for switching gets much weaker.
Three charging scenarios compared
Every car page on HonestRange computes your monthly running cost against a petrol comparator across three scenarios:
Home off-peak: This is by far the cheapest option. If you have a driveway with a 7 kW home charger and a dedicated EV tariff, your cost per mile is very low. The headlines about EVs being cheap are true in this situation.
Home standard rate: This is still cheaper than petrol for most cars, but the difference is much smaller. Without an EV tariff, you pay the standard rate set by the price cap, which is several times higher than the off-peak rate.
Public rapid only: Here is the honest truth. If you rely only on public rapid chargers, the savings compared to petrol can become so small that an EV might not save you much money. We are upfront about this, as most sources are not. Should you buy an EV if you can only use public charging?
Monthly cost: energy + VED + the 2028 road charge
Your monthly running cost includes your energy bill and road tax. Right now, EVs pay the standard-rate VED, which is about £16 per month. Starting in the 2028/29 tax year, a per-mile charge of about 3p is expected to be added. For someone driving 10,000 miles a year, this adds about £25 per month.
Our cost model includes both charges, and you can use a toggle to see the effect of the 2028 charge. For a full breakdown, see our 2028 mileage tax explainer.
The home charger payback
A home charger costs about £800 to £1,200 installed. However, the savings from using off-peak rates instead of standard rates or public charging can pay for the charger in less than a year if you drive a lot. This has a bigger impact on your EV running costs than the choice of car.
Our home charging guide explains what you need, how much it costs, and how to find a cheap tariff.
EV running costs: what you actually pay each month
Beyond the electricity bill, EV running costs include road tax, insurance, servicing and tyres. Road tax is currently the standard VED rate of about £190 per year. Insurance tends to be slightly higher than petrol equivalents for the same car size, though this varies by model. Servicing is cheaper: no oil changes, no exhaust, no clutch, and far fewer brake pad replacements thanks to regenerative braking.
For a driver doing 10,000 miles a year on a cheap overnight tariff, the total monthly running cost for a typical EV comes in at £60 to £100, compared to £150 to £250 for a comparable petrol car. You can see the exact breakdown for any model on our car pages.
When an EV doesn't save you money
We are one of the few sources willing to say this. If you cannot charge at home and rely on public rapid chargers, an EV may only be slightly cheaper per mile than a fuel-efficient petrol car. If you drive very few miles, the savings might not make up for the higher purchase price. Also, if you mostly drive short urban trips but sometimes need to tow or travel long distances, range anxiety and charging time can become real concerns.
Enter your actual mileage and charging situation on any car page, and our model will give you an honest answer. If the numbers show that you may not save money, we will tell you that.