Businesses are continuing to review greener alternatives for their fleets as the UK moves towards its 2035 phase-out of new petrol and diesel car sales. While fully electric vehicles (EVs) are growing in adoption, concerns around charging infrastructure, upfront costs, and operational practicality remain for some businesses.
Hybrid vehicles offer a practical middle ground. They combine traditional combustion engines with electric power, helping fleets reduce fuel costs and lower emissions without fully committing to electric.
In this guide, we answer the key question: how do hybrid cars work? We’ll explain the different types of hybrid vehicles, how hybrid electric cars work in practice, the pros and cons for fleets, and whether they’re the right choice for your business.
What is a hybrid car?
A hybrid car is a vehicle that uses both an internal combustion engine (ICE) and an electric motor powered by a battery. By combining these two systems, hybrid vehicles improve fuel efficiency and reduce tailpipe emissions compared to traditional petrol or diesel cars.
The different types of hybrid cars
When understanding how hybrid electric cars work, it’s important to know that not all hybrids operate in the same way. There are two main hybrid system designs:
Parallel hybrids
In a parallel hybrid, both the electric motor and the petrol or diesel engine can power the wheels directly. The vehicle switches between the two power sources or combines them depending on driving conditions.
This is the most common system used in self-charging hybrids.
Series hybrids
In a series hybrid, the petrol or diesel engine does not directly power the wheels. Instead, it acts as a generator to charge the battery, while the electric motor drives the wheels.
This design prioritises electric driving but still offers fuel backup.
Some modern hybrids combine both systems in what’s known as a series-parallel hybrid, automatically adjusting for efficiency and performance.
Mild hybrid electric vehicle (MHEV)
Mild hybrids use a small electric motor to assist the combustion engine, but they cannot run on electric power alone. The motor supports acceleration and reduces engine strain, improving fuel economy slightly. However, emissions reductions are lower than those of other hybrid types.
Self-charging hybrid (Full Hybrid)
Often referred to as full hybrids, these vehicles can run on electric-only power at low speeds and switch automatically between petrol/diesel and electric. They recharge through regenerative braking and engine power, meaning there is no need to plug in.
This makes them a practical solution for high-mileage fleet drivers.
Plug-in hybrid electric vehicle (PHEV)
Plug-in hybrids offer a larger battery and can typically travel 30–60 miles on electric power alone (updated 2026 range averages). They must be charged using a wall box or public charger.
If regularly charged, PHEVs can significantly reduce fuel use. However, if drivers rely mainly on the engine, fuel efficiency benefits are reduced.
How do hybrid vehicles work?
Understanding how hybrid cars work starts with their dual powertrain system.
Hybrid vehicles combine:
A petrol or diesel engine
An electric motor
A high-voltage battery
A power control unit
The vehicle’s onboard computer continuously monitors speed, acceleration, battery charge level, and driving conditions. It automatically decides whether to:
Use electric power alone (typically at low speeds)
Use the combustion engine
Combine both for maximum efficiency
At low speeds or in traffic, the electric motor often powers the vehicle. During acceleration or motorway driving, the combustion engine takes over or works alongside the motor.
This intelligent energy management system is what makes hybrid vehicles more efficient than standard ICE vehicles.
How does hybrid regenerative braking work?
One of the key technologies behind hybrid efficiency is regenerative braking.
When a driver brakes in a conventional vehicle, kinetic energy is lost as heat through the brake pads. In a hybrid vehicle, regenerative braking captures energy that would otherwise be wasted.
Here’s how it works:
When the driver presses the brake pedal, the electric motor reverses its function.
Instead of drawing power from the battery, it acts as a generator.
The vehicle’s momentum turns the motor.
That movement generates electricity.
The electricity is sent back to recharge the battery.
This process improves overall efficiency and reduces brake wear, thereby lowering maintenance costs for fleet vehicles.
Regenerative braking is a major reason why hybrid electric cars work so efficiently in urban driving conditions.
Hybrid charging and refuelling
Self-charging hybrids do not need to be plugged in. They recharge automatically through regenerative braking and engine power.
Plug-in hybrids (PHEVs), however, must be connected to an external power source. Charging times typically range between 2 - 5 hours, depending on charger speed and battery size.
Unlike fully electric vehicles, plug-in hybrids can still operate on their combustion engines when the battery is depleted. This reduces range anxiety but means regular charging is essential to maximise efficiency and reduce emissions.
As hybrid vehicles still rely on petrol or diesel, they require regular refuelling. However, fuel consumption is generally lower than that of equivalent ICE vehicles.
Pros of hybrid vehicles
Hybrid vehicles are becoming increasingly popular, with over 445,000 plug-in hybrids on the road in the UK. They offer many environmental and financial benefits, which is why they’re so appealing to businesses.
Some of the main advantages of hybrid vehicles include:
Fewer tailpipe emissions help to protect the environment.
Fuel efficient, saving businesses money.
Often require less maintenance than their ICE counterparts.
Convenient charging makes them an ideal choice for drivers on the move.
Lower road tax and a reduction in the benefit-in-kind (BIK) rate.
Lower Benefit-in-Kind (BIK) rates remain attractive for company car drivers in 2026 (particularly for low-emission PHEVs).
Reduced urban emissions may help meet Clean Air Zone requirements.
Cons of hybrid vehicles
Although hybrid vehicles have their advantages, they are not always a practical choice for drivers.
The main challenges of hybrid vehicles are:
More expensive to purchase than petrol and diesel vehicles.
Maintenance and replacement of the EV battery can be costly.
Limited towing capacity, as this can drain the batteries in a hybrid vehicle.
Regular access to a charger is required for a plug-in hybrid, which can be impractical for drivers who regularly travel long distances.
Real-world MPG depends heavily on driver charging behaviour (particularly for PHEVs).
Higher upfront purchase price compared to equivalent ICE models.
Hybrid vehicles continue to play an important role in fleet decarbonisation strategies in 2026. They provide flexibility, improved efficiency, and lower emissions while maintaining operational practicality.
If your fleet still relies on petrol or diesel vehicles, you can continue benefiting from our wide range of fuel cards, designed to reduce admin time and provide detailed transaction reporting.
Compare fuel cards using our online tool or speak to our team on 0113 202 5110. If you're expanding into electric or plug-in hybrids, explore our EV charge card solutions to support your transition.
FAQs: Hybrid cars explained
How do hybrid cars work compared to petrol cars?
Hybrid cars use both an electric motor and a petrol or diesel engine. Unlike traditional vehicles that rely solely on fuel combustion, hybrids switch between power sources or combine them to improve efficiency and reduce emissions.
How do plug-in hybrid cars work?
Plug-in hybrid cars work by using a larger battery that can be charged externally. They can drive on electric-only power for short distances before switching to the combustion engine.
Are hybrid cars good for fleets?
Hybrid vehicles can reduce fuel costs, lower emissions, and offer tax advantages. For businesses transitioning toward electrification, they provide a practical stepping stone. You can read more about the benefits in our guide to the benefits of hybrid vehicles for fleets (insert internal link here using that anchor text).
What is the difference between hybrid and electric cars?
Hybrid vehicles combine fuel and electric power, while fully electric vehicles run solely on battery power and must be charged externally.
