What is a plug-in hybrid, or PHEV?

Plug-in hybrids are an ideal compromise if you're unsure if a fully-electric car is for you. We explain all.

Electric cars come with a lot of jargon. There are hybrids, mild hybrids, battery electric vehicles, fuel cell cars and then something called a plug-in hybrid electric vehicle (PHEV). All of these are electric cars to varying degrees, and all of them work slightly differently.

A plug-in hybrid, or a PHEV, is an electric car that’s effectively a bridge between a conventional hybrid and a fully electric vehicle. While a hybrid will use its battery and electric motors to drive the car under certain circumstances, it doesn’t have to be charged. Instead, the car’s internal-combustion often tops up the electric batteries on board.

A fully electric car, on the other hand, doesn’t have an internal-combustion engine, and its batteries have to be charged externally by a cable.

A PHEV can be thought of a middle ground between a full electric vehicle and a hybrid. It has a battery pack that requires charging through a cable connected to the grid, and its electric motors can solely drive the car, but it also has an internal-combustion engine to take over driving duties when the battery runs out of energy.

How does a PHEV work?

Plug-ins generally come with a medium-sized lithium-ion battery pack that’s connected to an electric motor. The Mitsubishi Outlander PHEV, for example, has a 13.8kWh battery. Plug-ins also feature an internal-combustion engine, usually a petrol unit.

The lithium-ion batteries are charged from the grid, meaning you will need to plug the vehicle in. Usually, at slow speeds the electric drivetrain does all of the driving, until its battery runs out or more power is needed from the petrol unit.

A typical range from a PHEV is around 30 to 40 miles on electric power, after which the car will run on the internal-combustion engine.

However, the battery doesn’t have to be empty for the engine to come on. This can happen if the electric vehicle system is too cold or hot, or while features such as the heater are on. In some cases, the engine will come on if petrol hasn’t been added for several months. This is often a sign for drivers to top up the car with newer fuel to avoid damaging the engine.

Advantages of a PHEV

Plug-in vehicles address one of the big concerns about electric vehicles, which is range. Many buyers looking to switch to an electric car may be worried about how far they can get in a pure electric vehicle, and the time it takes to recharge the batteries.

PHEVs don’t have this issue, as they also feature an internal-combustion engine that takes over the driving duties from the electric vehicle drivetrain. This means a daily commute of anywhere between 15 and 20 miles can easily be done in electric mode. When it comes to do longer trips you won’t have to worry about the batteries running out, as the car will automatically switch to the internal-combustion engine.

With a PHEV you will also pay less or no vehicle tax, depending on the type of vehicle you have and when you bought it.

However, there are a few drawbacks. Because plug-ins effectively come with two different powertrains, they weigh more than conventional cars. This has an effect on the ride, with plug-ins often feeling heavier and harsher, especially on small roads.

It also means the engines on board can suffer when it comes to fuel economy – the heavier the car, the more the engine has to work to propel it forward.

Are PHEVs tax free?

Whether your plug-in is completely tax free depends more on when you bought it rather than the type of car you have. In April 2017, the Department for Transport introduced a new set of Vehicle Excise Duty bands. The new rates applied to all new cars registered after 1 April 2017.

Under the current VED rates, only cars that are zero emissions – meaning they pollute 0g/km CO2 – are exempt from VED. Owners of those that pollute even one gram of carbon dioxide will have to pay.

Because PHEVs are not entirely zero emissions – given that they feature a petrol unit – owners will have to pay VED. The rates then depend on the type of car you bought. For example, the best-selling Mitsubishi Outlander PHEV emits 41g/km CO2. This means new models bought today will be exempt from the first-year VED rates, but will be charged £130 for subsequent years.

However, if you had bought your Outlander PHEV on or before 31 March 2017, you would pay no tax for the vehicle. This also applies for all PHEVs registered before the same date, any used purchase will be tax exempt.

How do I get the most out of my PHEV?

Just like a regular electric vehicle, there are many ways to maximise your plug-in’s battery range. Try to accelerate smoothly and steadily when in full electric mode. Rapid acceleration and braking will reduce the range.

Also consider switching off things such as the air-con, as this draws current from the batteries, too.

One of the big differences is tyre condition and pressures. Properly inflated tyres will reduce road resistance and improve the electric vehicle range/fuel consumption.

How do I charge a PHEV?

Charging a PHEV is the same as charging an electric car. The first thing you need to do is make sure you know the type of plug your car requires. Most PHEVs today come as standard with a Type 2 plug. However, some – such as the Outlander PHEV, for example – features a Type 1 connector.

At home, you can use a standard three-pin plug to charge your PHEV, but this will take several hours. The exact time depends on the size of your batteries. Mitsubishi estimates a three-pin plug will take around five hours to top up the 12kWh battery on board the Outlander PHEV.

To find the nearest public charging station, log on to www.zap-map.com and use the map feature to find stations nearby. You can also select stations based on the type of charging plugs.

Click on each of the stations, and you can see whether they are currently occupied, and what kind of fees they charge owners.