What is a hybrid car & how does it work?

Electric cars are becoming more and more popular and with the 2035 electric switchover on the horizon, that’s not set to change. But for those of us who aren’t ready to make that full-electric car leap just yet, there are hybrid cars.

What does hybrid car mean?

In short, a hybrid car is a mix of both worlds — that is, it uses both traditional fuel in the internal combustion engine (ICE) and electric power in its motor. Hybrids come in a variety of types, with each working in different ways.

Some hybrids blend the power of both energy sources to drive, some rely on petrol purely to power the electric batteries. Whatever the case, in order to be defined as a hybrid, a car must use electric power alongside a standard gasoline engine.

Why get a hybrid car?

Using two fuel sources might sound like twice the effort when it comes to upkeep, but if you’re selling your car and on the hunt for your next vehicle, there are plenty of reasons to consider a hybrid:

• Consumes less fuel for lower running costs
• Emits less CO2 and may be exempt from LEZ and ULEZ charges
• Company cars pay less Benefit-In-Kind Tax
• Potentially exempt from the London congestion charge

How do hybrid electric cars work?

Hybrids work differently depending on their type — there are multiple different options, each working in its own unique way. As of 2021, the types of hybrid are:

• Full hybrid
• Mild hybrid
• Series hybrid
• Plug-in hybrid

The main point of difference between each of these is in their ‘drivetrain’ or ‘powertrain’ which, in simple terms, are the components in a vehicle that give power to the driving wheels. For some hybrid vehicles, this power comes from the engine, in others, only the batteries, and some models can use both.

Full hybrids

Also known as a ‘parallel hybrid’, full hybrids use a combustion engine and an electric motor to power the car. Both energy sources can also be used independently. The most common type of hybrid car, full hybrids mainly use electric batteries to aid with fuel economy.

For low-speed stop-start driving around town, they can rely purely on electricity. The regenerative braking system produces electricity for the batteries every time you decelerate. In the event of batteries running flat, the car can still drive using the gasoline engine alone.

You can find parallel hybrid models from car brands such as:

• Toyota
• Nissan
• Honda
• Ford
• Kia
• Lincoln

Mild hybrid cars

Mild hybrids use the same mix of gasoline engine and electric batteries, but the two cannot be used interchangeably. Like full hybrids, braking helps generate kinetic energy for the batteries.

It’s worth noting that this means the engine kicks in when the batteries need it, not when you put your foot down as with a petrol or diesel car, which can be a little unnerving to a new driver.

Mild hybrid vehicles are often the cheapest way to own a car that uses electricity alongside a standard ICE engine. The following brands currently offer mild hybrid models:

• Suzuki
• Mercedes
• Audi

Series hybrid

In a series hybrid, there is usually no connection between the combustion engine and the wheels, meaning the powering of the car is purely down to the electric motor. The engine powers the electric batteries, extending their range, which is why this model is also known as a range extender hybrid.

This model is especially good for stop-start driving, making them a popular choice for London taxis where reduced CO2 emissions result in exemptions from the ULEZ charge. On the other hand, it’s not the best option for performance driving as the combustion engine can’t provide assistance like a full hybrid.

Brands that currently have series hybrid models include:

• BMW
• Chevrolet
• LEVC

Plug-in hybrids

Plug-in hybrids, also called PHEVs, are models that can be manually plugged in to charge up the batteries. They’re the closest option to a 100% electric vehicle and can be driven purely on electricity as well, but can also use both the combustion engine and their batteries.

Plug-in hybrids can cover a lot more ground than other models on electricity alone due to having much larger batteries, meaning far less fuel use. The downside is that the batteries add a lot of weight to the car, so if you did ever have to rely on the engine alone to get you home, it would actually result in far less economical fuel consumption.

Plug-in models are available from the following brands:

• BMW
• MINI
• Toyota
• Mitsubishi
• Porsche

Self-charging hybrid cars

Full hybrid, mild hybrid and series hybrid vehicles can all be considered self-charging as they don’t need to be plugged in to power up the batteries. Instead, the batteries are charged through regenerative braking or the engine.

How long do hybrid car batteries last?

As a general rule of thumb, hybrid batteries should be changed every 100,000 miles. Many hybrid vehicles also come with warranties of around 10 years so you’ll be covered for any faults in the batteries. For a regular household, it would take around 10 years to drive 100,000 miles.

What is range anxiety?

Range anxiety refers to when an electric vehicle runs low on battery i.e. anxiety that the car won’t stay powered for the range needed. It’s one of the reasons hybrids are a great gateway model for electric vehicles, as there are still traditional petrol engines to serve as backup.

The term is still commonly used on the topic of EVs but that’s not to say it’s substantiated — most electric cars are more than able to withstand the demands of a regular household, and at a lower cost compared to traditional fuel.

Key components

Whichever model you choose, the basic components of a hybrid remain the same.

Auxiliary battery

Provides the power to start the car before the traction battery takes over and powers accessories.

DC/DC converter

This converts the high-voltage power from the traction battery to lower-voltage power needed to charge the auxiliary battery.

Electric generator

Generates energy every time the car brakes.

Electric traction motor

Draws energy from the traction battery to turn the car’s wheels.

Exhaust system

A three-way catalyst reduces emissions as the exhaust system passes gases from the engine to the tailpipe.

Fuel tank

The tank for traditional fuel like petrol.

Internal combustion engine (ICE)

The standard engine found in any non-hybrid/electric car.

Traction battery

Stores electricity for the electric traction motor.

Transmission

Takes power from either the engine or the electric motor to drive the car.

How much is a hybrid car?

Hybrids are becoming increasingly more available. In 2021, you can get your hands on a hybrid vehicle for around £20,000, and the increasing popularity of environmentally-friendly cars means the second-hand market is growing too. Prestige brands have also joined the fray — Porsche offer a hybrid model for a little over £100,000.

Will hybrid cars be banned in 2035?

The government’s plan to crack down on petrol and diesel cars in 2035 doesn’t extend any special protections to hybrid cars. So, while they’re not quite as bad as an ICE-only vehicle, they do still use an ICE engine, and that’s precisely what the ban targets.

So, should you sell your hybrid car in preparation for the big change? The answer is up to you — even after 2035 you’ll still be able to drive a hybrid you already own, or buy a second hand one. The change will stop the manufacturing any cars that run on petrol or diesel.

Of course, if you want to get ahead on selling your car and going electric, now could be a great time. Once the ban is in place, the reputation of ICE engines is going to be naturally tarnished and you can expect this to reflect in your car valuation and contribute to car depreciation.

Are they worth it?

So…are hybrid cars good? In terms of environment, at least compared to a classic ICE car, yes. For other considerations like charge exemptions based on CO2 emissions, the answer is also yes, though this window of opportunity may be closing.

The government will be cracking down on hybrids just the same as ICE vehicles come 2035, so while hybrids are a good way to make the change, it may be wiser to make the full leap to 100% electric.

If it’s a matter of price, then it’s worth noting that the Plug-In Vehicle Discount can get you up to £2,500 off your new EV so long as it’s on the eligibility list — hybrids are not eligible. The cost of journeys made using an EV versus a traditional ICE vehicle is also significantly cheaper.

Frequently asked questions about hybrid cars

Do hybrid cars pay congestion charge?

At present, the majority of hybrids are exempt from the London congestion charge, but it’s important to double-check your vehicle’s emissions rating. It will need to be Euro 6 compliant to qualify for the Cleaner Vehicle Discount.

After October 2021, eligibility criteria will change to cover only full-electric and hydrogen fuel vehicles. On December 25th 2025, the discount will be discontinued completely and all vehicles will have to pay the congestion charge.

Are all hybrid cars automatic?

No, mild hybrids with manual transmission exist, but they are in the minority. Most hybrid models are automatic due to the careful balancing act of regenerative braking, dual-fuel use and general power. Hybrid and electric cars use clever technology to analyse and re-analyse this balance every second of your journey, and a manual transmission would be very disruptive.

Do you have to charge a hybrid car?

Plug-in hybrids can be charged by plugging them in, but they can also be charged through regenerative braking or through the ICE. While most hybrid models can use the electric motor alone to drive or turn to the ICE when batteries are depleted, they are not designed to run on an empty gas tank.

What is a self-charging hybrid car?

‘Self-charging’ is the term used to differentiate between hybrid vehicles that don’t need to be plugged in to charge compared to those that do. Essentially, that means any model that isn’t a plug-in hybrid. The other models of hybrid use the ICE engine and braking to power the motor. As they don’t need any actual charging session, they can be considered self-charging.

Ready to sell your car?

Ready to learn more about valuing, maintaining, and selling your car? Check out more of our guides here, covering everything from hybrid and electric car depreciation, to converting your car to dual-LPG fuel.

• Hybrid cars – should you buy or sell?
• What is a hydrogen fuel cell car?
• Electric cars — the ultimate guide 
• Electric cars — should you buy or sell?
• LPG cars — the ultimate guide
• What documents do I need to sell a car?
• Do electric cars pay the congestion charge?
• How & where to charge your electric car at home and on the road
• How long does it take to charge an electric car?
• Do electric cars need servicing?
• Electric car FAQs