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How much does charging an electric car cost? Is it cheaper than petrol?

Your electric car charging costs are simple to calculate. Here’s how to work it out

Published: 07 Apr 2023

There are plenty of reasons for going electric: that pesky CO2 stuff, for one thing. But there’s another incentive for making the switch other than doing your bit for the polar bears: electric car charging costs.

You see, charging an electric car has been - historically, at least - cheaper than filling up with conventional fuel. And that means over the course of electric vehicle ownership, you could save yourself a lot of money in running costs. Really.

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There are, of course, a couple of important caveats: to make the numbers work, you will need to do the majority of your charging at home. This is where electricity is most affordable (even with energy costs ballooning) and some tariffs will allow you to make the most of cheaper overnight rates when demand is low.

Public charging points - including the so-called ‘rapid’ chargers popping up at motorway service stations - tend to be a lot more expensive. And while they’re a godsend for topping up quickly on a long journey, you will be paying for the privilege. So much so that the price per mile of driving might not be that much different to that of a petrol or diesel car. Boo! Hiss!

It also depends on the amount of driving you do. If you only venture out to the shops very occasionally or have a short, irregular commute (hello working-from-homers), then the full benefits of an electric car will be much more subtle.

But if you drive a reasonable distance every year, and you can plug your electric car into a wallbox on your driveway or in your garage, you’re onto a winner. Now all that remains is to work out exactly what the costs are. Please continue to scrolleth…

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How do I work out electric car charging costs?

It’s quite easy to figure out how much charging is costing you. All you need to know is the size of the battery, the range of the car, and the unit price of the electricity per kilowatt-hour (kWh).

For argument’s sake, let’s use the Kia Niro EV as an example: the latest version of that comes with a 64.8kWh battery, and on paper it can do 285 miles on a full charge.

Also for argument’s sake, let’s say you’re charging at home and you’re paying 34 pence per kilowatt-hour for the electricity. This is based on the capped average unit price set from October 2022 until March 2023, although it varies a little by region.

That means a full charge of the Niro EV from flat will cost you 64.8 times £0.34, which is… a snip over £22. Sounds pretty tempting when the average price of a tank of fuel peaked at over £100 in June 2022.

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We must remember that the range of the Niro EV is 285 miles according to the official lab tests. In real-world driving you’ll see less than this, but the same goes for the ‘official’ fuel economy of a petrol or diesel car. More on that in a bit.

Anyway, 285 miles from 64.8kWh gives us… about 4.4 miles per kilowatt-hour (mi/kWh, or sometimes mipkWh). This unit is basically mpg for electric cars, and 4.4 is pretty good. The most efficient electric vehicles will sneak over 5.0 in the summer, while the least efficient will struggle to get above 2.0. Eep.

Right, last bit of the puzzle: if you’re getting 4.4mi/kWh and you’ve paid £0.34 for that energy, your running cost per mile is… less than eight pence. £0.077, to be exact.

How much cheaper is electric than petrol or diesel?

Okay, now let’s work out how that compares to internal combustion. And we can use the Niro again here, because there’s also a petrol version of that car. And yes, before you mention it the latest petrol Niro is hybrid as standard, but there’s no plugging in involved and all the energy powering that car ultimately comes from the fuel tank (42 litres, if you were wondering).

On paper the Niro can achieve 64.2mpg, and according to the RAC the average price of unleaded in the UK at the time of writing is 148.74 pence. There are 4.546 litres in a gallon, so one gallon costs around £6.76.

All we need to do is divide 64.2mpg by the price of a gallon and we get running costs per mile of… 9.63 pence. Which means it’s almost two pence per mile cheaper to drive the EV.

I’ll be honest, I thought the savings would be… bigger.

You’re right to feel a little aggrieved. A couple of years ago domestic electricity cost around 13-14p/kWh, so it has almost trebled, and could rise even more when the government cap on the unit price ends. The sharp increase has wiped out a big chunk of the saving EV drivers were making on their running costs, and there’s no telling when things will settle down again.

The thing to remember is that fuel prices have also been volatile: it wasn’t long ago that fuel was pushing £2 per litre as Russia’s invasion of Ukraine, a weak pound relative to the dollar and supply issues drove the price sky high. At that point EV drivers could feel pretty smug; less so now.

It looks like energy prices - whether that’s for electricity or fuel at the pumps - will continue to fluctuate for the next year or two, so sometimes the savings from going electric will be big and other times they won’t be. After then we’ll hopefully have a better idea of the long-term trend.

But previously running costs of electric vehicles were about a third - and sometimes a quarter - of their combustion engine equivalents, and that made the ownership case much stronger as purchase prices of EVs tended to be thousands of pounds higher. The more electricity costs, the longer it’ll take you to earn back that difference.

How much does it cost to charge in public?

That depends on which charging provider you use. Tesla drivers using the firm’s Supercharger network currently pay a peak rate of 67p/kWh, although drivers of other brands have to pay 77p. Ionity rapid chargers will set you back 69p/kWh; Chargemaster/bp pulse chargers start from 65p/kWh for pay-as-you-go customers with no membership.

In other words, charging in public is probably twice as expensive as charging at home. So if you don’t have your own home charging unit installed and you need to rely on third party chargers, it ain’t gonna be cheaper. At least, not at the moment.

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