Charging an EV on the road costs more than you think

The headline case for an electric car is running cost, and on a home tariff it is genuinely compelling. The picture changes considerably once you are dependent on the public network.

The two worlds

Home charging on an off-peak tariff can be a few pence per kWh, which puts the cost per mile in low single figures. This is where the "a fraction of petrol" claim comes from, and for a home-charging commuter it is accurate.

Rapid and ultra-rapid public charging costs several times that. At motorway service areas in particular, the per-mile cost can approach, and occasionally exceed, a comparable diesel.

The same car can therefore cost 3p a mile or 20p a mile depending entirely on where it was charged.

The same car, five ways to charge it

An EV doing about 3.5 miles per kWh:

For comparison, a 45 mpg petrol car at 145p a litre costs about 14.6p a mile.

So an EV charged at home overnight is roughly a seventh of the petrol cost. The same car charged exclusively on motorway rapids costs more than the petrol car it replaced.

Why this matters for business driving

A driver whose work is local and who charges at home has energy costs far below the 55p approved rate, although that rate is also meant to cover insurance, servicing, tyres and depreciation.

A driver whose work is long-distance and who charges on the network has a very different reality, and it is the one nobody models when they choose the car, because the comparison was made against home charging.

If you are choosing a vehicle for business use, the honest question is not "what does it cost to charge" but "where will I actually be charging, on the journeys I actually make".

The rate does not care

For your own electric car, approved mileage rates apply exactly as for petrol: 55p for the first 10,000 business miles in the tax year, then 25p, for journeys from 6 April 2026. There is no separate electric rate and no adjustment for how you charged.

For a company electric car, the advisory electricity rate applies instead. HMRC now publishes two figures: from 1 September 2026, 7p a mile for home charging and 15p a mile for public charging. Both are revised quarterly alongside the Advisory Fuel Rates.

Using the 55p approved rate on a company EV is a common and costly mistake.

The reimbursement gap

The awkward case: a company EV driver who charges at their own expense and is reimbursed at the advisory electricity rate. Depending on tariff and where they charge, the home or public figure may over- or under-compensate them, and the treatment of charging reimbursement has changed in recent years.

If that is your situation, check the current guidance rather than the arrangement you set up when you got the car.

Knowing your own number

The only way to know what your EV actually costs per mile is to record what you paid and how far you went. The same discipline as logging fill-ups, with charging sessions instead.

The reason it is worth doing: the gap between the assumed cost and the real one is much wider for electric cars than for petrol, because the price per unit varies by a factor of five depending on where you plugged in.

Sources

• Advisory fuel rates (HMRC)
• Travel, mileage and fuel rates and allowances (HMRC)
• Business travel mileage for employees' own vehicles (HMRC)
• Increasing mileage rates (HMRC policy paper)
• Vehicle tax rate tables (DVLA)

General information, not tax advice. Advisory rates change quarterly.