How much could you save by switching from petrol to electric?

How much could you save by switching from petrol to electric?

Petrol and diesel prices are soaring – but electricity costs are rising too. Here’s how to work out just how much you’re paying to travel a mile in your electric vehicle (EV) compared to one powered by fossil fuels.

One of the most common questions people ask when thinking about buying an electric vehicle is: how much money will I save by switching to an EV?

While many people are attracted to electric vehicles because they are less harmful to the environment, the cost of refuelling factors into the equation for most motorists.

Everyone knows that driving a mile in an electric vehicle will usually cost a lot less than in one with an internal combustion engine, but by how much? And for how long will this be the case? Do soaring electricity prices actually make petrol and diesel a cheaper option?

At the time of writing (April 2022), the answer to this last question is a resounding no. Running an EV is considerably cheaper than running a car powered by diesel or petrol. Let’s take a look at the numbers…

The average price per litre in April 2022 for unleaded was £1.63 and £1.77 for diesel. For a typical car that uses 5.4 litres of fuel per 100km (62 miles), that works out as follows:


£1.63 x 5.4 litres = £8.80 per 100km / per 62 miles

Which equates to:
8.8p per kilometre / 14p per mile


£1.77 x 5.4 litres = £9.55 per 100km / per 62 miles

Which equates to:
9.5p per kilometre / 15.4p per mile

Now to the $64,000 question: what does it cost to charge an EV – and how much does that work out per mile?

How much does it cost to charge an electric vehicle?

We’ll start by looking at the costs of charging a vehicle at home, as this is usually much cheaper than using one of the commercial charge points that are dotted around the UK.

We’ll also assume that your home is currently on the new capped electricity tariff (as almost all households are).

Different EVs have different sized batteries – ranging from as little as 30kWh to as much as 100+, but insurance specialists NimbleFins say that the average is around 57kWh – meaning that the average electric vehicle currently costs around £16 to fully charge at home.

But what does that mean per mile? Well, according to assorted reports found online, the average EV will consume 0.346kWh (kilowatt hours) of electricity for every mile it runs.

So how much will 0.346 kWh actually cost you?

At the time of writing, the price of a single kWh in the UK had just shot up, and was now capped at around 28 pence. Therefore, a single mile would cost 0.346 of this – which is 9.7p.

So, with prices based on the current electricity price cap:

The average cost of driving an EV in the UK (that has been charged at home) is around 9.7p per mile.

Significant savings when switching to an EV

Based on the above figures, running a car on petrol works out at almost 50% more expensive than electricity, while diesel is around 60% more expensive.

Petrol: 14p a mile

Diesel: 15.4p a mile

EV: 9.7p a mile

* Prices shown are for illustrative purposes, will vary from vehicle to vehicle and are not guaranteed.

If you drive 10,000 miles a year, the savings could be more than £400 a year when comparing an EV with a petrol car, and almost £600 a year with a diesel.

Note that these savings won’t be as good if you use a commercial EV charging point.

These are significant savings – and don’t forget that forecourt prices could easily go up. An article in The Guardian in March 2022 warned that petrol could soon hit £2.50 a litre and diesel £3.

Note also that there are many electric vehicles around that can easily beat the average cost per mile quoted above (though admittedly the same is true for diesel and petrol cars, too).

The BuyaCar website says it is possible to get EVs that can travel more than five miles per kWh (the comically small Renault Twizy actually manages 6.1). An EV capable of 5 miles per kWh should cost less than 6p a mile to run.

There may be other ways to save money when charging an EV, too – some energy tariffs offer off-peak hours, for example. EDF points out that it pays to shop around for suppliers whose off-peak tariffs meet your needs. A Renault Zoe, which has a 30 kWh battery, needs far less charging time then a 100 kWh Tesla, for example.

For further reading, and a detailed breakdown of the running costs of different vehicles, we highly recommend this report from Which? (note, however, that it was written before the recent hikes in electricity prices).

There are also savings to be made on road tax, too: the Government website clearly states that electric vehicles (not including hybrid cars) are exempt from road tax. This could save you more than £100 per year – a lot more if you had your eyes on an expensive petrol or diesel model.

Summing up: why electric vehicles make sense

Once you’ve had an EV charge point installed at your home – a quick and painless process that normally takes just a few hours – you’ll be able to run your vehicle knowing that it is probably costing significantly less per mile to run than a petrol or diesel car.

Plus you’ll also be able to refuel from the comfort of your own home. If your cheapest garage is at the supermarket 10 miles away and refuelling would have required three visits a month, that’s 60 wasted miles a month on refuelling. Or 720 miles a year. Or more than £100 in fuel.

Switching to an EV couldn’t be simpler. There are Government grants that help to bring down the vehicle’s purchase price, EV charge points are available in a range of different styles, and you also get to wake up every morning knowing two important things:

1/ That you’re doing your bit for the environment. And…

2/ That you can have a lie-in the next time there’s a panic on at the fuel pumps!

* The above figures were based on April 2022 data. Electricity, petrol and diesel prices are all likely to have changed since this article was written.

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