Charging electric cars at key public points has risen to nearly £50 – making them more expensive to run than petrol engines.
Oil giants BP and Shell – which oversee the UK’s largest grids – charge 79p and 85p per kWh respectively.
The price has been creeping up to reflect rising wholesale electricity costs.
Meanwhile, the price of petrol has dropped to around 144p a liter, meaning a typical engine will cost around £72 to fill up.
As a result, the cost per mile for the electric VW ID.3 is 21.43p – compared to 13.03p for the Golf 1.5L, VW’s petrol equivalent.
RAC spokesman Simon Williams said: “As the government encourages families to buy electric cars, it will come as a big surprise to many that they can be more expensive to run using public chargers.”
“Of course, the running costs of charging at home are significantly lower. But this is only possible for those who have a driveway and can install a charger at their house.”
He called on the government to reduce VAT on public chargers from 20 percent to 5 percent to match the household electricity rate.
That costs 34p per kWh, so running an electric vehicle costs about 10p per mile, the RAC said.
From July the price will fall to 30p or 8.5 per mile as the price cap for household electricity falls.
This makes home-charged electric vehicles cheaper than petrol cars.
Wholesale electricity costs are also falling, so that both public and private charging should become cheaper.
However, owners of electric cars will also have to pay vehicle tax from 2025.
That should be £165 a year, up from £10 in the first year.
This comes after the Resolution Foundation called for a new road tax for electric vehicle owners at a recommended 6p per mile.
Meanwhile, the Asphalt Industry Alliance, the road construction industry, said heavy electric vehicles could potentially create more potholes.
Chairman Rick Green said: “Unclassified roads would not be designed to handle truck axle loads, so heavier electric cars could exacerbate existing weaknesses and thus accelerate the decline.”