What is a plug-in hybrid car?

Hybrids provide low emission motoring for the masses. But what is a plug-in hybrid car?

BuyaCar team
Oct 29, 2019

If you're looking for a new-ish car that is going to help you save money on fuel, as well as other costs like tax and ULEZ charges, the a plug-in hybrid might just be what you're looking for.

They don't just save you money either, as these environmentally-friendly cars are primarily designed to reduce carbon emissions and limit our dependance on fossil fuels. It's something of halfway-house between yesterday's petrol and diesel engines and tomrrow's electric motors.

Emissions regulations are becoming stricter and stricter, so manufacturers have been force to develop this technology, and more and more of them are introducing better and better plug-in hybrids to their line-ups.

Most of these cars introduced through 2019 are capable of covering over 20 miles on electric power alone, which will be more than enough for most people to take a trip to the shops, and can help fuel economy figures can climb to staggering figures of over 200mpg.


It's all sounding good so far, read on to find out more about how plug-in hybrid cars work, and which of them are available to purchase right now.

What is a plug-in-hybrid car?

Not to be confused with other types of hybrid cars, the plug-in variant requires the battery to be charged in the same way an all-electric car would be - hence the 'plug-in' part. Other hybrid variants use the engine itself to charge the battery, and do not support static charging.

With a battery and motor like electric cars, plus a petrol or diesel engine, plug-in hybrids should offer the best of both worlds. Fully charged, they’ll drive for 20-30 miles on electric power before the engine takes over. This means fuel economy is exceptional on short journeys, but less impressive on longer trips.

Plug-in hybrid cars: the good

✔ Electric range of more than 20 miles
✔ Cheap to run assuming you plug it in
Low company car tax

Mild hybrid cars: the not-so-good

Needs to be charged frequently
Fuel economy not as good as a diesel on long runs
Reduced luggage space

How plug-in hybrid cars work

In many respects, a plug-in hybrid works in a similar way to a regular hybrid. For propulsion, it has a petrol or diesel engine, and an electric motor. The electric motor is powered by a battery pack.

Regular hybrids charge their batteries on the move via the petrol engine, and regenerative braking.

Plug-in hybrids have larger, more powerful batteries. This is good for electric range, but they do need to be charged independently. In other words, they need to be plugged in.

Do plug-in hybrid cars improve fuel economy?

Yes and no. If you regularly charge your plug-in, and only use the engine as a last resort, you’ll see very good combined figures. Toyota’s Prius has an official fuel consumption of 283mpg. Most people probably won’t even get close to this, but, most people will achieve 95-100mpg if they charge regularly and do a lot of town driving.

If you don’t regularly charge the battery, expect mpg to be much, much worse. This is because you’re lugging around another 100kg worth of batteries which will act as a dead weight.

Incidentally, electric power performs much better around town than on the motorway. The Toyota Prius plug-in will cover around 30 miles around town on electric power, but only 20 miles at motorway speeds.


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