The EV Guide

For an EV, the basic calculation is simple:

electricity price ÷ miles per kWh = electricity cost per mile

Imagine an EV averaging 3.5 miles/kWh.

Same car.

Same journey.

Very different cost.

That is why statements such as ‘This EV costs 3p per mile’ are meaningless unless you know the electricity price behind them.

You need to compare the EV against the car you would otherwise drive.

For a petrol or diesel car, the same principle applies:

fuel price + vehicle efficiency = cost per mile

For example, purely illustratively:

Compare that with an EV at:

Suddenly the importance of charging price becomes obvious.

These are examples, not current tariff or fuel-price assumptions.

This is where EV comparisons can become misleading.

Suppose an EV saves £800 a year in fuel.

If it costs £8,000 more to acquire than the alternative car, that matters.

Likewise, a used EV bought for less than an equivalent petrol car may present a completely different proposition.

So your comparison should eventually consider:

• purchase price or finance
• fuel or electricity
• insurance
• servicing and maintenance
• vehicle tax
• likely resale value or depreciation

Not every cost needs to go into one giant calculator.

But you should know which costs you have included before calling one car ‘cheaper’.

Battery EVs do not have many of the routine engine-related service items found in petrol or diesel cars.

But EVs still have:

• tyres
• suspension
• brakes
• air conditioning
• windscreen wipers
• MOTs
• insurance
• repairs

So:

lower maintenance does not mean no maintenance.

One old EV assumption is now out of date:

electric cars are no longer automatically exempt from Vehicle Excise Duty.

For the 2026–27 tax year, electric cars registered from April 2025 pay £10 in their first year and then the £200 standard annual rate. Some higher-list-price EVs can also attract the expensive-car supplement.

There is another known future cost too.

From 1 April 2028, current legislation introduces a mileage-based Electric Vehicle Excise Duty. The initial rate for battery-electric cars is 3p per mile.

That should not make or break today’s EV decision by itself.

It should simply be included rather than assuming EV taxation will remain as it was several years ago.

Battery capacity is measured in kWh.

Vehicle efficiency is often shown in miles/kWh.

Put the two together and you get a useful idea of range.

The battery hasn’t shrunk.

The amount of distance you get from each unit of electricity has changed.

Real-world range changes with conditions.

Temperature, speed, road type, heating or air-conditioning, load, tyres and driving style can all affect how far the car travels on the same amount of stored energy.

That means one fixed range figure can never describe every journey.

Motorway driving on a cold winter evening is not the same as urban driving on a mild summer day.

Imagine your driving looks like this:

You do not necessarily need a car capable of driving that entire 300-mile journey without stopping.

You need to decide whether:

the normal journeys fit comfortably

and

the occasional long journey can be charged conveniently enough for you.

Those are separate questions.

This is where charging capability begins to matter alongside battery size.

For a long journey, the practical question isn’t simply:

“How far can I drive?”

It is also:

“When I do stop, how quickly can I add enough range to continue?”

A car with slightly less battery capacity but strong rapid-charging performance may be more convenient on repeated long trips than one with a bigger battery that recharges slowly.

We’ll deal with charging in the next chapter.

Cold conditions can reduce range because the battery and cabin both need energy and the vehicle can be less efficient.

That does not mean an EV suddenly becomes unusable in winter.

It means your sensible range assumption should include winter rather than planning every journey around the car’s best possible conditions.

If you have suitable parking, charging at home can be the simplest way to live with an EV.

You arrive home.

Plug in.

The car charges while it is parked.

You do not need to wait until the battery is empty.

EV charging often works more like charging your phone than visiting a petrol station:

1. use some
2. →plug in
3. →start again with more

A charger rated at 7 kW is describing power.

Very roughly, operating at 7 kW for one hour transfers around 7 kWh of energy before allowing for losses or any limits elsewhere in the system.

So if a car needed around 35 kWh added:

35 kWh ÷ 7 kW ≈ 5 hours

as a simple starting estimate.

The vehicle, charger and electrical supply can all place limits on the actual charging rate.

This is where EV running costs can become particularly attractive.

Suppose your car does 3.5 miles/kWh.

The vehicle hasn’t changed.

When you bought the electricity changed.

Great EV economics can therefore come from matching the car with the right tariff rather than simply buying the most efficient car.

Solar can potentially charge an EV during the day.

But avoid thinking:

“I’m charging my car for free.”

If that solar electricity could instead have been exported for payment, using it in the car has an opportunity cost.

Putting the solar into the car may still make sense.

But its economic value isn’t automatically zero-cost.

The question is:

“What is the best use of that kWh?”

That is the same principle used throughout Home by Numbers.

Public charging serves a different job.

It can provide:

• charging for people without home access
• top-ups while parked somewhere
• rapid charging on long journeys

Public rapid charging can cost considerably more per kWh than home electricity.

That means somebody relying on it heavily can have very different running costs from somebody charging almost entirely at home.

Current UK public-chargepoint rules also require clearer price information and, for certain chargers, payment and reliability standards designed to make public charging easier to use.

Imagine your annual EV energy came from:

Your true cost isn’t any one of those tariffs.

It is the blend.

1. how many kWh
2. →where they come from
3. →the price at each source

That is why Home by Numbers models the mix rather than assigning every EV one generic charging price.

If workplace charging is available, it can materially alter the economics.

It might be free, subsidised or charged at a set rate.

Treat it exactly like any other electricity source:

how much of your annual charging can realistically come from it, and what does each kWh cost?

When comparing EVs, I would want to understand:

• purchase price or finance cost
• usable battery capacity
• realistic efficiency
• expected real-world range
• AC charging capability
• DC rapid-charging capability
• battery warranty
• vehicle warranty
• insurance
• servicing
• equipment and specification
• what home charging will require

Those numbers work together.

A single impressive specification does not tell you whether the vehicle suits you.

You may see 100 kW, 150 kW or 250 kW used prominently in EV advertising.

Those figures can be useful.

But charging power varies during a charging session.

For long journeys, the better customer question is:

“How long does this car take to add the amount of range I normally need at a charging stop?”

That is more useful than simply asking which vehicle displays the largest maximum kW figure.

Rapid charging receives most of the attention because the numbers are larger.

But if you mainly charge at home, the car’s normal AC charging capability can matter more often.

Check that your vehicle, your home chargepoint and your electrical supply work sensibly together.

A 22 kW-capable chargepoint does not automatically mean every car will accept 22 kW from it.

Check it.

Do not assume every EV battery has identical warranty terms.

If you are buying used, also check:

• remaining battery warranty
• where practical, evidence of battery condition or state of health

A used EV with a healthy battery and a specification that suits your journeys can be a completely different financial proposition from buying new.

Government support can affect the purchase price, but eligibility changes.

At the time this guide was checked, eligible new electric cars could receive a model-specific Electric Car Grant of up to £3,750, with a second band worth up to £1,500.

Some chargepoint grant schemes also remain available to eligible households and properties.

Treat grants as a current discount to verify before buying — not a permanent assumption in the economics.

If home charging is central to your EV plan, treat the chargepoint as part of the purchase decision rather than something to think about afterwards.

Check:

• where the vehicle will park
• where the charger will go
• the cable route
• the electrical work required
• who handles any network notification
• whether your chosen charger works with the tariff or smart-charging approach you intend to use

Compare like with like.

Do not compare:

cash price of one vehicle

with:

monthly payment of another

and call one cheaper.

If salary sacrifice is available, compare the actual reduction in take-home pay plus anything included — such as insurance, maintenance or tyres — against the real cost of acquiring the alternative car.

Likewise, understand:

• mileage limits
• initial payments
• end-of-contract conditions
• what you own at the end

The EV drivetrain does not make a poor finance deal into a good one.