It's a debate that rages on: could you really save money by switching to an electric vehicle?

While EV converts are prone to lauding the cost–saving benefits of their 'green' cars, refusers sticking by their petrol and diesel motors argue that any financial reward of making the switch – if any – is outweighed by the lack of charging practicality and range anxiety.

But with all the finances laid out on the table, which option is genuinely the cheapest right now?

Motoring magazine Auto Express has been crunching the numbers to reveal the truth – and shared its findings exclusively with Daily Mail and This is Money.

Using five examples of popular cars where there is a petrol and EV equivalent, it has looked at the total three–year ownership costs, including everything from 'refuelling' to purchase price, maintenance, and tax.

And it has found that while electricity can be up to 70 per cent cheaper than petrol as a fuel, steep purchase prices, painful depreciation and higher insurance bills is wiping out the savings of making the transition to EVs.

Auto Express compared the five petrol and electric car head–to–heads over a three–year ownership period where drivers cover 36,000 miles.

It used 'real–world charging behaviour and industry pricing data' when making its calculations to provide the most accurate reflection of what motorists can truly expect to pay over the 36–month period.

Tom Jervis, consumer reporter at Auto Express who ran the comparison, said 'Electric cars are still dramatically cheaper to charge than petrol models are to fuel, but our data shows that doesn't automatically mean they're cheaper to own.

'Once you factor in depreciation, insurance and upfront prices, the savings can disappear very quickly.'

In fact, in only one of the instances was the electric option cheaper over the petrol. In another case, the cost difference was negligible.

As such, the study suggests drivers – for the time being at least – are better off purchasing petrol models while they're still readily available in showrooms before the 2030 ban on sales of new combustion engine cars. 

Charging vs fuelling

Using average domestic off–peak electricity rates – and basing the average UK split for home and public EV charging (84 per cent and 16 per cent respectively) according to ZapMap – Auto Express found electricity to be consistently less than half the price of petrol.

Charging a Volkswagen ID.3 over 36,000 miles costs just over £1,500, compared with almost £3,900 to fuel an equivalent petrol Volkswagen Golf.

The Vauxhall Corsa Electric delivers the most dramatic saving, costing around 70 per cent less to charge than the petrol Corsa over the same distance.

However, that advantage is incredibly sensitive to charging behaviour. 

When public rapid chargers are used at typical UK rates, charging the ID.3 rises to almost £4,500 over three years, making it more than 15 per cent more expensive than the Golf.

This is not helped by the higher VAT rate on public chargers (20 per cent) compared to home charging (5 per cent). That said, the Treasury is reportedly considering slashing taxation on public charging to match that of VAT on domestic electricity.

'We found that charging an EV at home costs less than half the price of petrol in every scenario we tested,' Tom said. 'But drivers relying on public rapid chargers could actually end up paying as much, or even more, than petrol, which completely changes the financial equation.'

Servicing

Electric cars typically save between £200 and £300 on servicing over three years compared to their petrol equivalents.

'Thankfully, driving an EV does come with several other cost savings over ICE [internal combustion engine]; given that there are fewer moving parts in an electric car, the price of servicing an EV is consistently lower,' Tom explains.

The Skoda Elroq, for example, requires just one service in three years, costing £318, compared with £552 for a petrol Skoda Karoq. 

However, the biggest saving in the test was the two Corsa models; the EV cost £283 in servicing across the period compared with £986 for the petrol version – a difference of more than £700.

Depreciation

Depreciation overwhelmingly dominates EV ownership costs, as This is Money has been reporting in recent years.

The poor residual value of EVs compared to their petrol counterparts dramatically eats into the potential cost savings accrued from cheaper recharging versus refuelling with unleaded. 

For instance, the Vauxhall Corsa Electric is projected to retain just 33 per cent of its new price after three years with depreciation accounting for more than 80 per cent of its total ownership cost.

This compares to 47 per cent for the petrol model. 

The Volkswagen ID.3 loses more than £21,000 in value across the same period versus £18,000 for the Golf.

As for the premium BMW i4 EV, it loses nearly £32,000, retaining just 40 per cent of its original price compared to the petrol–powered 4 Series Gran Coupe, which holds onto half (50 per cent) of its new value after three years.

'In four out of the five comparisons we looked at, the electric version depreciated faster than the petrol equivalent,' Tom said. 

'In some cases, depreciation alone wipes out years of cheaper charging.'

Insurance and road tax

The investigation found that EVs can cost almost £1,000 more to insure over three years.

The petrol BMW 4 Series Gran Coupe M Sport costs £3,867 while the battery–powered i4 rings in £278–a–year pricier to total £4,700 over the same period. 

And while EVs used to benefit from road tax exemptions, they now face the same VED rates as petrol cars.

One small silver lining is that, from April, the threshold after which you must pay the annual £425 Expensive Car Supplement (ECS) will increase from £40,000 to £50,000 for EVs.

For petrol, diesel and hybrid cars, the ECS threshold remains at £40,000 – as it has done since it was introduced in 2017.

While this will be beneficial for many less expensive EVs, models like the BMW i4 still slips into the clutches of the ECS and therefore racks up more than £1,200 in road tax over three years.

Electric versus petrol: Which really is cheapest?

As the study shows, there were clear winners when it comes to specific models comparisons.

For example, the Skoda Elroq costs significantly less to own over three years than a petrol Karoq, undercutting its ICE equivalent by almost £5,000.

The Ford Puma Gen–E is also cheaper overall, but not by much – over three years and 36,000 miles it costs just £33 less.

In contrast, the petrol Vauxhall Corsa is more than £3,000 cheaper than the EV over the three-year period and, the VW Golf is around £1,300 cheaper than its EV alternative.

But the biggest difference of all is seen with the BMWs. 

The petrol 4 Series Gran Coupe M Sport is over £5,600 cheaper to run over the three years and 36,000 miles than the electric i4 M Sport.

However, Auto Express surmised that the cost of ownership can fluctuate dramatically depending on an individual's circumstances and motoring habits.

'The more miles you do, the more the advantage swings back towards EVs,' it said, as it urged drivers to 'look forensically at the specific car they want if financial prudence matters'.

Yet, the motoring title concluded that depreciation remains the biggest factor limiting the affordability of EVs.

And this gap could grow as manufacturers begin to scale back ICE car production in preparation for the ban on their sales this decade, ultimately pushing the value of in–demand used petrol and diesel cars higher. 

'There is no foregone conclusion here – electric cars are cheaper to fuel, but not automatically cheaper to own,' Tom said.

'Insurance and charging habits can dramatically alter the final bill, but depreciation remains the single biggest cost factor. 

'Our test shows that where there’s an obvious petrol and electric alternative from the same brand, two found conclusively in favour of the petrol car, two others were close and one was heavily in favour of the EV, once you take into account all of the running costs.'

Tom added: 'Electric cars absolutely can make financial sense, but choosing the right electric car really matters.

'Buyers need to look beyond fuel costs and do the maths before they plug in.'

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