Could petrol and diesel ever become cheaper than charging an electric car?
It is great to see petrol and diesel prices finally starting to come down below the £1.45/l mark since their peak of nearly £2.00/l (£1.90/l for petrol) a year or so ago. But as the prices are expected to continue to fall (RAC Fuel Watch), could they ever become cheaper than charging an electric car?
Let's find out by doing a two minute calculation. Pen and paper ready?!
The current Energy Price Guarantee keeps the cap on the domestic electricity rate at an average unit price of £0.33/kWh for standard variable tariffs. This will go even further down to £0.30 from July when the Energy Price Cap takes over, but let's use today's price for this comparison.
Let's assume a 20 miles/day commute, taking the weekly total to 100 miles:
With a diesel vehicle having a fuel efficiency of 40mpg, the fuel cost adds up to £16.48 based on £1.45/l at the pump. There are a few unit conversions to do to calculate this, so we suggest using the simple calculator at fuel-economy.co.uk
Now considering an electric vehicle with an average efficency of 4 miles/kWh, 100 / 4 * 0.31 = £8.25. This is about half the price of the diesel vehicle. Some of the latest EVs achieve 5 miles+/kWh but 4 miles/kWh is a good market average efficiency.
We can use the fuel-economy.co.uk calculator to find out how much the price of diesel needs to be to match the price of charging the EV, which is £0.73/l. The last time diesel cost that little was in 2003 and it's fair to say it will likely never come back to those levels.
The difference is even greater when signing up for an overnight off-peak tariff (£0.075/kWh, Octopus June 2023), with a total cost of only £1.88/l for the EV. That is a whopping 9x cheaper.
With public chargers, the cost benefit is significantly lessened. With an average price of £0.63/kWh (Zapmap Price Index, April 2023), the same 100 mile journey costs £15.75 which is roughly the same price as the diesel car.
From the above, we can see that an EV will save money as long as it is charged from home. Fuel prices would need to go down to around 75p/l to become less expensive than running a home-charged EV. Relying on the public network costs approximately the same price as running a combustion engine vehicle.
