The short answer
- Fuel for 8,000 miles in a 45 mpg petrol car costs about £1,405 a year at 173.8p a litre.
- An electric car charged 80% at home on an 8p tariff and 20% on 75p rapid chargers costs about £489.
- Charged entirely at home on that tariff, it costs £183; entirely on rapid chargers, £1,714, more than petrol.
- With a £5,000 higher price, the total cost over six years is close; higher mileage tips it towards electric.
What to compare
A fair comparison includes everything you pay over the time you keep the car:
- The purchase price, after any discount or grant.
- Fuel or electricity.
- Servicing, tyres and repairs.
- Car tax and, from 2028, the electric mileage charge.
- Insurance.
- What the car is worth when you sell it.
The calculator adds these up year by year and shows when, if ever, the electric car catches up.
Fuel versus electricity
A petrol car doing 45 mpg uses about 0.1 litres a mile, which costs 17.6p at 173.8p a litre. An electric car doing 3.5 miles per kWh uses 0.29 kWh a mile. What that costs depends entirely on the price of the electricity.
| Where you charge | Price a kWh | Cost a mile |
|---|---|---|
| Overnight EV tariff | 8p | 2.3p |
| Home, standard price cap | 26.32p | 7.5p |
| 80% home tariff, 20% rapid | 21.4p average | 6.1p |
| Rapid public charger | 75p | 21.4p |
Where you charge changes everything
With a driveway and an overnight EV tariff, an electric car is very cheap to run. Without home charging, costs depend on finding cheaper public chargers, such as slower on-street or supermarket chargers, rather than motorway rapid chargers.
A worked example over six years
- Petrol: £25,000 car, running £2,505 a year, worth 35% at the end£31,278
- Electric: £30,000 car, running £1,589 a year plus 3p a mile from 2028, worth 30%£31,495
In this case the two are almost level. Without the 2028 mileage charge, electric would be £743 cheaper. With all charging at home, electric would cost £29,657 in total, saving £1,621.
How mileage changes the answer
| Miles a year | Petrol | Electric | Cheaper |
|---|---|---|---|
| 4,000 | £27,064 | £29,547 | Petrol by £2,483 |
| 8,000 | £31,278 | £31,495 | Petrol by £217 |
| 15,000 | £38,652 | £34,903 | Electric by £3,749 |
The more you drive, the more the lower running cost counts. At 15,000 miles a year, the electric car pays back its higher price in the fourth year.
Purchase price and resale value
The price gap between electric and petrol cars has narrowed, and used electric cars have become much cheaper. If you can buy an electric car for the same price as the petrol one, it is £3,283 cheaper over six years in the example.
Resale values for electric cars have been less predictable than for petrol cars, as battery technology and new models move quickly. The calculator lets you set the value at the end for each car, so you can test a range.
Servicing, tyres and insurance
- Servicing
- Fewer moving parts, no oil changes
- Brakes
- Last longer thanks to regenerative braking
- Tyres
- Can wear faster because of weight
- Servicing
- Oil, filters, spark plugs, clutch
- Brakes
- Normal wear
- Tyres
- Normal wear
Insurance for electric cars is often a little higher, as repairs can be more expensive. Get quotes for both cars before deciding.
Car tax and the 2028 mileage charge
Since April 2025, electric cars pay car tax: £10 in the first year and then the £200 standard rate, the same as petrol. New electric cars over £50,000 pay the £440 expensive car supplement in years 2 to 6. From April 2028, electric cars are due to pay 3p a mile on top, which is £240 a year at 8,000 miles. The car tax calculator has the details.
Company cars and salary sacrifice
The sums are very different through work. Electric company cars are taxed at 4% of the list price in 2026/27, against around 30% for a typical petrol car, and salary sacrifice saves income tax and National Insurance. See the EV salary sacrifice calculator.
Practical questions
- Range: most new electric cars manage 200 to 300 miles in real driving, less in cold weather.
- Home charger: fitting one typically costs £800 to £1,200, and you need off-street parking.
- Long trips: rapid chargers add 20 to 40 minutes per stop and cost much more than home charging.
- Battery health: most batteries have an 8-year warranty and degrade slowly.
Who saves most
Electric usually wins if you
Can charge at home on an EV tariff, drive 8,000 miles a year or more, and keep the car for several years.
Petrol may still be cheaper if you
Have no home charging and rely on rapid chargers, drive few miles, or pay a large premium for the electric car.
EV tariffs explained
Most energy suppliers now offer tariffs for electric car owners with a much cheaper rate for a few hours overnight. Some charge a low rate only while the car is charging, managed through the charger or the car’s app. The trade-off is a higher daytime rate for the rest of the house, so check the whole household bill, not just the car.
If you work from home and use a lot of electricity in the day, a standard tariff at the 26.32p price cap may suit better. Even then, charging costs about 7.5p a mile, well under half the cost of petrol.
If you have no driveway
Many households, especially in towns and cities, have no off-street parking. For them, the cost of running an electric car depends on what public charging is nearby. Slower on-street and destination chargers are usually cheaper than rapid chargers, and some councils offer lower rates for residents. Some workplaces offer free or cheap charging, which is not taxed as a benefit.
Set the share of public charging in the calculator to match your situation. At 100% public charging at 75p a kWh, the electric car in the example costs £1,714 a year in electricity, more than the petrol car’s fuel.
Buying a used electric car
Used electric car prices fell sharply in recent years, which makes them good value for buyers. Before buying, ask for a battery health report, check how much of the battery warranty is left, and check the real-world range on the kind of journeys you do. A used car bought for the same price as a petrol equivalent removes the purchase gap entirely.
Where hybrids fit
A self-charging hybrid cannot be plugged in but uses less fuel in town. Enter its real mpg as the petrol car. A plug-in hybrid can run on electricity for short trips and petrol for long ones; it is cheapest when you charge it every night and most journeys are within its electric range. From April 2028 plug-in hybrids are due to pay 1.5p a mile on top of car tax.
If prices change
Fuel and electricity prices both move. Petrol rose sharply in September 2026 and fuel duty is due to go up by 5p a litre in early 2027. Electricity prices change every quarter under the price cap. The calculator assumes today’s prices for the whole period, so try a range: a higher petrol price and a higher electricity price, to see how robust the answer is.
Common mistakes
- Assuming all charging is at home. Count holidays and long trips on rapid chargers.
- Comparing list prices only. Running costs and resale value matter as much.
- Forgetting the 2028 mileage charge. It narrows the gap for high-mileage drivers.
- Using the official mpg for the petrol car. Real-world economy is usually lower, which favours electric.
The full cost per mile
Putting everything on a per-mile basis makes the comparison easier to picture. In the six-year example at 8,000 miles a year, the petrol car costs about 65p a mile in total, including the drop in its value, and the electric car about the same, at 66p. Fuel and electricity are only a small part: depreciation is the biggest single cost for both.
That is why the purchase price and resale value matter so much. A cheaper used electric car, or keeping either car for longer, lowers the cost per mile more than any change in fuel or electricity prices.
Before you switch
- Work out your real yearly mileage from your last two MOT certificates.
- Check whether you can charge at home or at work, and what EV tariffs are available.
- Get insurance quotes for both cars.
- Compare total costs over the years you will keep the car, not just the monthly payment.
- Test drive on the journeys you do most, especially if you have long trips or cold winters.
- For a used electric car, ask for a battery health report.