Electric vehicles are usually sold on running costs, and petrol cars on purchase price. Comparing the two properly means looking past a single fuel fill-up or electricity bill and adding up ownership costs over a realistic period, such as 10 years and 100,000 miles. Using DESNZ weekly road fuel price data, AA and RAC figures on running costs, and typical domestic and public charging tariffs, the answer is closer than either side of the debate tends to admit, and it hinges on one practical detail: how much charging happens at home.
Why the comparison is harder than it looks
Most EV-versus-petrol comparisons quote a single pence-per-mile figure, which flatters whichever fuel is cheapest that week. Petrol prices move with crude oil and duty changes tracked by the AA Fuel Price Report; electricity costs move with wholesale gas prices and, crucially, with which tariff and charging location a driver actually uses.
A fair comparison needs three things held constant: the same annual mileage, the same ownership period, and a distinction between home and public charging, since the gap between them is far larger than the gap between different petrol stations. This piece uses 10,000 miles a year for 10 years, a common assumption in DVSA and industry lifecycle studies, giving 100,000 miles in total.
Purchase price and depreciation
A typical family-sized petrol car costs around £24,000 new and might retain roughly £3,000 in resale value after a decade of use, giving a net purchase cost of about £21,000. A comparable EV, such as a mid-size hatchback, typically costs closer to £30,000 new; assuming a resale value of around £6,000, the net purchase cost works out at roughly £24,000.
That £3,000 upfront gap is the most visible part of the EV premium, and it is the number most buyers fixate on in a showroom. It is also the smallest part of the total 10-year picture once fuel and electricity costs are added, which is where the comparison starts to shift.
Running costs: fuel versus electricity
Over 100,000 miles, a petrol car averaging 45mpg uses roughly 10,100 litres of unleaded. At an average pump price of around 145p/litre, in line with recent DESNZ weekly averages, that comes to about £14,600 in fuel over the decade.
An EV averaging 3.5 miles per kWh needs roughly 28,600 kWh over the same distance. If 80% of that charging happens at home on a typical domestic tariff of around 25p/kWh, and the remaining 20% uses public rapid chargers at around 60p/kWh, total electricity cost comes to roughly £9,100. But if all charging is done on public rapid networks, the same 28,600 kWh costs closer to £17,100, more than the petrol car's entire fuel bill.
The verdict: home charging is the deciding factor
Adding purchase cost, fuel or electricity, and servicing together over 10 years and 100,000 miles gives roughly £40,600 for the petrol car, £36,100 for the EV charged mostly at home, and £44,100 for the EV relying mainly on public rapid charging.
The conclusion is not that EVs are cheaper or more expensive in the abstract, but that the answer depends almost entirely on driveway or off-street access to a home charger. Drivers who can charge overnight on a domestic tariff are likely to save several thousand pounds over a decade. Drivers without off-street parking, dependent on public rapid networks, may find a petrol car remains the cheaper option once every cost is counted, not just the one on the fuel receipt.
The takeaway
Over a realistic 10-year, 100,000-mile ownership period, an EV charged predominantly at home comes out several thousand pounds cheaper than an equivalent petrol car, mainly through lower running costs rather than purchase price. Relying on public rapid charging removes most or all of that advantage. Before choosing on cost grounds, check charging access first: it matters more to the 10-year total than the badge on the boot.
