Should I buy a plug-in hybrid car?

Zero-emission commuting - if you keep the batteries charged - and no range anxiety: does a PHEV make sense for you?

Chris Rosamond
Sep 2, 2021

A PHEV, or Plug-in Hybrid Electric Vehicle, is a car that combines the ability to drive for a limited number of miles on pure electric power supplied by a battery, with a traditional petrol or diesel engine that takes over automatically as the battery is depleted.

When that happens, the car must be plugged into a wallbox or other EV charger to top up the battery. Once charged, you get another stint of electric-only motoring with zero tailpipe emissions, until the battery is flat again.

From the driver’s perspective there are two key differences between a PHEV and an electric car (sometimes referred to as an EV), and the first and most significant is that a flat battery won’t bring your journey to an end. Because your car switches automatically to petrol or diesel power you can travel anywhere that’s in range of a filling station, just like traditional car drivers.

The other difference is that the distance you can travel in electric-only mode is substantially lower than in a fully electric car.

In theory, these cars offer the best of both from electric cars and conventionally fueled 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 brings down the cost of company car tax significantly.

But in reality, unless your primary motivation is scoring that company car tax break, these cars are best suited to a limited group of drivers who can do a large proportion of their driving on electric power and charge them up regularly. 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 the battery has depleted
Reduced luggage space to account for the batteries

Plug-in hybrid driving range

Early PHEVs would generally top out at around 15 to 25 miles of electric driving range, but nowadays the latest models are capable of much more than that. The BMW X5 xDrive45e manages 54 miles on electric power alone, for example, while the Ford Kuga PHEV will do 35 miles. Most seem to have settled on a range of between 35-40 miles.

As with electric cars, the actual range is dependent on a list of factors as long as your arm. Things like the temperature and whether it's raining affect this just as much as how fast you accelerate. Regenerative braking can add some juice back into the battery as you drive, but it won't be anywhere near enough for a full recharge.

For a plug-in hybrid car to manage a much longer range than this would require larger batteries, but the batteries in a plug-in hybrid already take up a significant portion of the car's space alongside the petrol or diesel engine. Manufacturers seem to have found a useful balance, as the average journey for most motorists is around 30 miles. The thinking is that most drivers will top up regularly and treat their PHEV as an electric car, using the engine only for longer journeys.

Often what makes a plug-in hybrid really stand out when you’re shopping for a car, is the extraordinarily high MPG numbers claimed for them. For example, the Toyota Prius PHEV is said to return up to 235mpg, while even the high-performance Porsche Panamera 4 E-Hybrid is said to be able to return up to 141mpg.

Unfortunately, though, real-world driving suggests actual MPG figures will be a lot lower for the average PHEV driver - some suggest by an average of around 40%.

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

To get the absolute best fuel economy from your plug-in hybrid car, you'll need to charge it regularly and make use of every mile of electric driving that you can. If you're spending a great deal of time under the power of the petrol or diesel engine then you're likely to find your fuel economy takes a dramatic turn for the worse.

If you are able to charge the batteries regularly, you might start to get close to the official economy figures often promised by plug-in hybrid manufacturers. In the case of a Toyota Prius Plug-in, this can be as high as 235mpg. 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.

Something like the Hyundai Ioniq is cheaper to buy in hybrid form, but plug-in hybrid and electric versions are almost identically priced. The key difference is that the electric version offers almost 200 miles on a full charge.

On the flip side, if you have no intention of plugging in your PHEV then its fuel economy is actually likely to be worse than a conventional car. That's because all you’re doing is using a petrol engine to lug around a couple of hundred kilos of batteries 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 plug-in hybrid is smaller than what you'll find in an electric car, 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.

There's a popular phrase that circulates among EV drivers, and is hugely applicable to PHEV drivers, too: 'ABC' - Always Be Charging.

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 BMW 330e M Sport (above) costs less than £80 per month in company car tax for taxpayers in the 20% bracket. A diesel-powered BMW 320d M Sport would be around £180 per month.

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 world, 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 its subsidy for buyers of brand new plug-in hybrid cars (there's still a plug-in grant worth up to £2,500 for new 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 hybrids available, and the list is growing. A ban on petrol and diesel power is fast approaching (the sale of brand new petrol and diesel cars will be banned in 2030), and the same is imminent for hybrids and plug-in hybrids. The next decade will likely see the coming and going of dozens of plug-in hybrid models as we prepare to transition to electric power.

There is a range of affordable and pricey models, from SUVs and crossovers to smaller hatchbacks and everything in between. It's worth noting that if you prefer the wind-in-your-hair feeling of a convertible, you'll be out of luck getting one of these in plug-in form.

Below are the current models on sale with plug-in options:

 

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