A guide to hybrid cars and how they work

10 September 2021 | Celia Topping

We’ve put together this article about the interior workings of a hybrid car, the charging process, and understanding the lingo. Hopefully it’ll answer all the questions you were too afraid to ask. 

What is a hybrid car?

A hybrid car runs on a combination of a petrol/diesel engine, and an electric motor, powered by a battery. In some cases, this just means the battery gives the engine an extra boost (mild hybrid). In other types of hybrid, the car can run solely on battery power – some for very short distances (full hybrid), others for up to 40 miles (plug-in hybrids). 

This all means lower carbon emissions because the petrol engine is assisted by electricity, and better fuel efficiency. Win win! 

Types of hybrid car

Full hybrid cars

A full, or parallel, hybrid uses both a petrol/diesel engine and an electric motor to drive the car – together or separately.

The battery can hold a small amount of electric charge, meaning it can give an extra boost to the combustion engine when they’re used at the same time. You can also switch to electric-only mode for very short distances, and at a low speed. The small battery is charged internally, by the engine, so it charges quickly and you don’t have to spend so much on fuel.. 

Mild hybrid cars

You might also have heard of mild hybrids being called self-charging hybrids. They’re similar in set-up to full hybrids. The main difference is the electric battery and combustion engine components can’t be used separately. 

The battery is charged by regenerative braking, where unused power is sent back to the car’s battery as you hit the brakes. This electric power is used to assist the petrol/diesel engine, but can’t power the car alone. 

Plug-in hybrid cars

A plug-in hybrid, or PHEV, is the hybrid most similar to a full electric car. It uses a larger battery, which can be plugged into a charger in the same way as an electric car. 

This means a PHEV can be driven by battery alone, with the range usually being between 20 to 40 miles. After this point, the petrol/diesel engine kicks in seamlessly, to speed you to your destination. You can then charge the battery at your leisure, when you get home, or at a public charging station. 

diagram how does a hybrid car work

For the full and mild hybrids, the electric battery pack is charged by the engine as well as via regenerative braking (the car’s way of recycling energy  through the braking system). This can be referred to as self-charging. When accelerating, the electric motor is powered by the charged electric battery, boosting the car's speed.

In plug-in hybrids (sometimes called PHEVs),  the electric battery can be charged via an external charge point.

What are the advantages of hybrids?

The 2 main advantages of a hybrid car are:

  • Lower carbon emissions
  • Less fuel needed

This is because the electric battery enables the car to be driven on electricity alone (except in mild hybrids). This means the petrol/diesel engine isn’t used as much as in normal cars.  

Hybrids also offer a smooth, quiet driving experience without clunky gear changes. They make a reliable stepping stone between a regular car and a fully electric car: they bring the benefits of electrification, without having to worry about running out of charge. 

What are the disadvantages of a hybrid car?

On the other hand, there can be some downsides:

  • A higher initial cost than petrol/diesel cars
  • Maintenance can be more expensive petrol/diesel cars
  • Insurance is more expensive petrol/diesel cars
  • They still produce carbon emissions
  • In the case of PHEVs, the battery needs to be charged frequently, as the range is only around 20 to 40 miles

But the good news is that hybrid costs will drop as more cars are developed and technology improves. 

Charging a hybrid car: how do hybrid cars charge?

It goes without saying that different types of hybrid cars charge differently. Full and mild hybrids charge their own batteries while on the move, via regenerative braking and the car being in motion. But plug-in hybrids are a bit different. Here’s how to charge your plug-in, at home or on the go

Where can I charge a plug-in hybrid car?

A plug-in hybrid can, in theory, be charged by any regular 13 amp plug. But of course, it’s a much bigger battery than the one in your mobile phone, so it’s faster to use a dedicated home charger

Alternatively, you can use the vast network of public charge points around the UK

How long does it take to charge a plug-in hybrid car?

Depending on the battery size, charging your hybrid via a regular plug socket can take from 3 to 20 hours. But using a specially installed 7kWh home charger takes around 4 to 8 hours. Most hybrids can only be charged at the slow public charge points, as their batteries won’t support the faster charge points. 

Read more about the different types of chargers, connectors and EV speeds in our comprehensive guide. 

electric car charging

Hybrid cars costs: what’s the average price of a hybrid car?

What does it cost to charge a plug-in hybrid car?

According to the Department for Business, Energy & Industrial Strategy (BEIS) the average cost for standard electricity in the UK in 2020 was 17.2p/kWh1. But if you add Charge Anytime to any OVO plan, you could be charging your plug-in hybrid for 7p per kWh, whenever you like.

It’s also handy to note that there are often free charge points available at some supermarket car parks, and some leisure and entertainment centres. Why not plug in for free while you work out, get the groceries, or watch a film?

Are hybrid cars expensive to insure?

Unfortunately, hybrid cars can be a little more expensive to insure than conventional cars, because the parts can be more expensive to repair and replace. But, with the market being so competitive, prices are being driven lower and lower.

Read more about electric car insurance and how much it costs in our informative blog. 

Are hybrid cars eligible for government grants?

There are various government grants and incentives for EV and plug-in hybrid car drivers. But only cars that can travel at least 70 miles on battery power, and have carbon emissions of less than 50g/km, can apply for a plug-in grant. 

This excludes the majority of hybrid vehicles, but there are some premium hybrids that fit the bill. Here’s a full list of eligible vehicles

Which hybrid cars are exempt from the London congestion charge and other clean air zone charges?

As of 25 October 2021, only pure electric cars will be allowed to enter the congestion zone for free. 

In the Ultra Low Emissions Zone, all electric and hybrid vehicles are exempt. 

Hybrid cars performance and maintenance 

A common misconception is that hybrid cars don’t perform as well as conventional cars, but technology has come a long way since the early days. 

How far can I drive with a hybrid car?

You can drive pretty much as far as you would in a conventional car. A typical PHEV will take you around 20 to 40 miles on the battery alone. But then the engine kicks in, taking you as far as a slightly-smaller-than-normal fuel tank allows.

Hybrids are getting better all the time  – the Toyota RAV4 Prime has an impressive full range of 600 miles on a full charge and a full tank!  

In full hybrids, the help of the electric motor allows you to travel longer distances without stopping for petrol.

How fast can a hybrid car go?

The top speed of a hybrid is faster than you can legally travel in the UK, at around 100 mph. Acceleration isn’t quite up to speed with petrol cars yet. So It might take a little longer to get going – but you’ll be able to zip along the fast lane with no worries.

Do hybrid cars drive differently to conventional vehicles?

Not really – no special skills are needed to drive a hybrid. In fact, for those used to manual driving, the automatic transmission might come as a pleasant surprise. 

There’s no need for concern about the transition from battery to engine, either. It’s seamless, and happens without any input from the driver. 

One thing to watch out for: because hybrids are controlled by on-board computers, it might sometimes feel like the engine has stalled when you stop temporarily, such as at a red light. This is because the engine automatically turns off when it’s not needed. But don’t worry, it starts immediately again when you need it to! 

Another difference that has attracted some criticism that hybrids are a bit slower to accelerate. Your typical hybrid will probably get you from 0 to 60 mph in about 10 seconds. But car manufacturers are producing faster cars all the time, with larger V-6 engines and more powerful motors, which will soon make hybrids as speedy as their petrol or diesel counterparts. 

Hybrid cars and the environment

car driving on road through forest

Efficiency and emissions of a hybrid car

The petrol/diesel engine in a hybrid vehicle means it still creates carbon emissions when you drive it. But, because there's also an electric motor and battery powering the car, it uses less fuel to cover the same distance. That’s why hybrids are more fuel-efficient, and produce fewer greenhouse gases.  

According to the 2018 SMMT New Car CO2 report2, new cars produce around 121g/km of CO2 from their tailpipes, with diesel cars emitting about 15 to 20% less than petrol cars. Hybrid cars can emit less than 100g/km. Generally speaking, choosing a lower emission model can reduce your running costs and put you in a lower, cheaper, tax band. 

Are hybrid cars better for the environment?

Because hybrid cars generate fewer carbon emissions than a conventional car, they’re better for the environment than a petrol/diesel car. But they’re not as eco-friendly as a fully electric car, which produces zero emissions on the road.

What is the difference between a hybrid and an electric car?

Simply put, an electric car (EV) is driven solely by an electric motor, which is powered by a battery. It can only be charged via an electric charger plugged into the car’s socket. 

Hybrid cars have 2 power sources: a petrol/diesel engine and an electric motor, powered by a battery. As we’ve seen above, some hybrids can be plugged in, but others can’t. 

In summary, is it worth buying a hybrid car?

Absolutely! Hybrid cars offer drivers cheaper journeys and fewer carbon emissions, but with the security of a petrol engine – getting rid of any range anxiety. 

But, if you want to cut your emissions completely and drive progress to net zero, you’d be better off going for a full electric car. After all, if you want to use a battery, why carry a petrol engine with you too?

What are the best hybrid cars on the market right now? 

That’s a great question, and luckily, we have all the answers! Check out our top 10 hybrid cars for every type of driver article on Planet OVO, and  you could be driving your carbon-kicking hybrid sooner than you think! 

Most popular questions about hybrid cars

Here are some answers to the most commonly asked questions about hybrid cars:

Do hybrid cars need to be charged?

Only plug-in hybrid cars need to be charged. All other types of hybrids get their electric charge through the fuel engine, so are fuelled in the same way as traditional cars. 

Are all hybrid cars automatic?

Nowadays, yes. There have been manual transmission hybrids in the past, such as the Honda CR-Z, but it’s unlikely there’ll be a shift in that direction again – it’s just not necessary in a hybrid car. 

What’s the lifespan of a hybrid car battery?

This totally depends on the model and make of the car. But most manufacturers give a warranty of around 8 years on hybrid technology. That’s around 80,000 to 100,000 miles. 

Are hybrid cars being phased out?

Yes and no. In November last year, the UK government announced that the production of new petrol and diesel engine cars will be banned from 20303

But hybrids that can drive a “significant distance” on electric power only could still continue production until 2035. So buying a full or plug-in hybrid now would still be a good idea, to reduce tailpipe emissions and cut fuel costs. 

Can you convert a petrol car to a hybrid?

Yes, you absolutely can. Most cars can be converted into a hybrid or fully electric vehicle for under £1000. If you really love your petrol car, and don’t want to switch, it’s certainly worth thinking about – especially for classic cars! 

What OVO can offer you as an EV/hybrid driver

Add Charge Anytime to any OVO plan for free – and start driving for under 3p a mile4 when you smart charge your EV from home.That's just 7p per kWh at any time.

If you don't already have an EV charger at home, take a look at the range of EV chargers we install. And they're all Charge Anytime compatible.

So why not get a quote, and switch to OVO today? You could be charging your EV and saving money sooner than you think.

Sources and references:




4. The 3p a mile claim is based on an EV customer driving the UK average of 7,000 miles at an average of 3 miles per kWh. The Charge Anytime add-on rate on 01/11/2023 is 7p per kWh. Actual sum per mile is 2.3p. Individual costs will vary based on your vehicle efficiency and driving style.