Should I buy a plug-in hybrid car?

Zero-emission town driving - if you remember to charge the batteries - and a petrol engine for long journeys: is a PHEV right for you?

Chris Knapman
Aug 18, 2020

A plug-in hybrid electric vehicle (PHEV) combines the ability to drive for a number of miles on electric power alone with a petrol or diesel engine to take over when you run out of charge. And when you get home, you can plug the car in and recharge the batteries, or even top up en route for maximum fuel economy.

In theory, these cars offer the best of electric and conventional vehicles with fewer downsides. They are increasingly popular thanks to their low official emissions ratings (based upon the assumption that you'll regularly charge the battery), which bring down the cost of company car tax. And, if you need to cover many hundreds of miles, you can fill up with petrol or diesel - as with any conventional car - to cover the longest of journeys without having to wait to recharge.

But in reality, these cars are best-suited to a limited group of drivers who can drive a large proportion of miles on electric power and charge them up regularly. Unlike a standard hybrid car, such as the original Toyota Prius, these cars - as the name suggests - can be plugged in to charge up their large batteries. Read on to see if a plug-in hybrid car is right for you.


Why you would buy a hybrid car

✔  Zero-emission electric range often 20+ miles ✔  Can be cheap to run if regularly plugged in
✔  Low company car tax

Why you wouldn't buy a hybrid car

Need to be charged frequently
Poor fuel economy once battery has depleted
Reduced luggage space  

Plug-in hybrid driving range

Generally speaking, the electric range of a PHEV is between 15 and 25 miles although, as with a full electric vehicle (EV), this will vary according to how smoothly you drive, your speed and the external temperature (cold weather reduces the range).

The range is fairly standard, as manufacturers think that they have found the right balance of cost and space (larger batteries are expensive and bulky), as well as distance between charges: the average journey for most motorists is well under 30 miles. The thinking is that most drivers will be able to travel on electric power for the majority of trips - provided drivers remember to charge up regularly.

What makes a plug-in hybrid really stand out is that it also includes a conventional engine that takes over when the battery power runs out. Combined with the battery power this can result in a range of about 400 to 500 miles from a single charge and a tank of fuel, depending on the car in question.


How to use a plug-in hybrid car (PHEV)

In reality it doesn’t make any sense to drive a PHEV on battery power, then rely on the petrol engine for many more miles because you don't get the benefit of cheap electric running. Instead you are best off plugging in little and often, using the petrol engine only when strictly necessary.

Do so and you might start to get close to the official economy figures of such cars, which in the case of a Toyota Prius Plug-in can be as high as 283mpg. However,  if this is the type of driving you typically do you might as well get a fully electric car and not have the expense of an unnecessary petrol or diesel engine and the reduced economy of having to carry this extra weight around.

On the flipside, if you have no intention of plugging in your PHEV then its fuel economy is actually likely to be worse than a conventional car’s, because all you’re doing is using a petrol engine to lug around a couple of hundred kilos of battery pack for no discernible benefit.

Some plug-in hybrids also have a function to use the petrol engine as a generator to charge the battery, but doing so drastically increases fuel consumption and is therefore not good value for money.


Plug-in hybrid charging time

The battery in a PHEV is smaller than in a EV, which in turn means charge times are reduced. Use a rapid charger and a plug-in hybrid such as the Mitsubishi Outlander PHEV can be topped up in 25 minutes, whereas if you use a slow charger it can take around five hours.

Either way, the premise is the same as with a full EV in that owners are encouraged to charge at those times when the car wouldn’t be in use anyway, such as overnight.


Buying a plug-in hybrid (PHEV) company car

Plug-in hybrids can make great company cars because their low emissions figures bring down the cost of tax substantially. For example, a 2018 BMW 330e M Sport (above) costs £1,360 a year in company car tax for 40% taxpayers, although the car is no longer available as new. A diesel-powered BMW 320d M Sport is £3,371.

These cars’ emissions figures are based on a laboratory test that every car must undergo, and which flatters plug-in hybrid cars. In the real word, you’ll use much more fuel and emit far more carbon dioxide on longer journeys where the engine is producing most of the power, than the official figures suggest.


Plug-in hybrid car prices

Adding electric power to a petrol or diesel car makes hybrid cars more expensive than conventional vehicles. That’s a particular problem with plug-in hybrids because they have large numbers of costly batteries.

In some cases, the lower fuel costs and tax can more than pay for the higher price, but that recently became less likely after the government withdrew a £2,500 subsidy for buyers of many brand new plug-in hybrid cars (there's still a plug-in grant worth £3,500 for pure electric cars).

Used plug-in hybrid cars are often available for considerably less than a brand new car, and they come with the same company car tax benefits.


Car tax for plug-in hybrid vehicles

Buying a used plug-in hybrid could save you the annual cost of car tax: most models that were on the road before April 2017 are exempt from the tax because it was calculated under an old system.

Every new car sold since April 2017 is taxed using a new method, which is only free for fully electric cars. Other cars are subject to a £140 annual flat rate of tax from their second year on the road, which is discounted by £10 per year for hybrids.


Plug-in hybrid cars on sale now

There’s a diverse range of plug-in hybrid cars on sale, with different manufacturers using the technology to achieve various objectives. Toyota, for example uses the technology to maximise fuel economy in its plug-in Prius, even going so far as to offer an optional solar panel that sits within the car’s roof to top up the battery (slowly).

Others, such as BMW, have used plug-in hybrid technology as a way to create a new kind of eco-friendly sports cars such as the i8, which is scintillatingly quick despite only having a 1.5-litre Mini engine under the bonnet.

There's an increasing contingent of hybrid SUVs that make use of plug-in hybrid technology including the Mitsubishi Outlander PHEV, Volvo XC60 and XC90 T8 versions, the smaller Mini Countryman Plug-in Hybrid (seen at the top of this page) as well as the recently-launched plug-in models of the Range Rover and Range Rover Sport. These offer emissions-free driving on the school run and plenty of space for family weekends away.

Then there are the company car-friendly options, including plug-in versions of the Mercedes C-Class, Audi A3, BMW 3 Series and Volkswagen Passat.

Some of these cars have been temporarily withdrawn from sale, as a result of new mandatory emissions tests which have increased the official CO2 and mpg figures of many vehicles. However, they are all available as used cars, for which the earlier figures still apply.


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