What is a self-charging hybrid?
We explain the pros and cons of a self-charging hybrid, and explain how it works
While 'hybrid' can refer to any vehicle that uses a combination of petrol or diesel and electric power, 'self-charging hybrid' is a term that has appeared fairly recently.
Used most commonly by Toyota and Lexus, the term describes a car that can travel on electric power alone, but can't be plugged in to charge like plug-in hybrid (PHEV) cars can. The true definition of 'self-charging hybrid' has barely changed from when such vehicles were described simply as 'hybrids' – before plug-in hybrid cars ( explained here) started to appear.
Cars referred to as hybrids or self-charging hybrids use one or more small electric motors to assist the conventional petrol or diesel engine, giving it a helping hand when accelerating. Most hybrid cars can also be driven at low speeds and for short distances using electric power alone, which saves fuel and reduces exhaust emissions.
Hybrid models are designed to excel in urban environments, where cars are typically driven slowly in lots of stop-start traffic. Here, it’s possible for the combustion engine in a hybrid to be inactive for long periods of time, saving fuel and avoiding polluting the air. Drive more quickly out of town or on the motorway, though, and the conventional engine will need to run, reducing the hybrid benefits.
After several decades on sale, hybrids have gone from being a very niche proposition to being reasonably commonplace. Toyota has been a major player in bringing hybrid technology to the mainstream, with its flagship hybrid model being the Toyota Prius. The Japanese manufacturer has sold over 10 million hybrid vehicles, introducing the technology across most of its model range, from the Yaris supermini to the RAV4 SUV, as well as the Lexus UX self-charging hybrid.
This guide introduces how hybrid cars work and explains whether choosing one could save you money.
How does a hybrid work?
Most hybrid (or self-charging hybrid) cars feature a petrol engine (although diesel hybrids are available), an electric motor and a small battery pack. As you drive along, some power from the engine and kinetic energy recuperated from slowing down and braking is used to charge the battery pack – this is what leads some manufacturers to use the term 'self-charging'. Then, as you accelerate, electricity from the batteries powers the electric motor and helps the car gain speed, making the petrol engine’s job easier and improving fuel economy.
When enough charge is in the battery pack, most hybrid vehicles can also pull away just using electricity and travel for a short distance at low speeds, using no fuel at all. This can be particularly handy in traffic jams, car parks and town centres where you don’t want to create air pollution.
Some hybrid vehicles, like the Toyota Prius, allow you to choose how much energy you put into the batteries when you release the accelerator. If you choose a higher level, you can learn to allow the recuperation of energy to slow you down, putting more charge into the battery pack and reducing wear and tear on the brakes. Of course, you’ll still need to use the brake pedal to come to a halt or to brake suddenly or in an emergency.
What are the pros of driving a hybrid car?
If you drive a hybrid in built-up areas, with lots of traffic, the technology can keep your petrol or diesel engine switched off for a high proportion of your journey, reducing running costs and cutting air pollution.
For this reason, hybrid models tend to emit less CO2 than conventional models, which qualifies them for several incentives. For a start, the Benefit-in-Kind (BiK) bands used to calculate company-car tax are based on CO2, so hybrid cars tend to be more affordable for business users to drive, with a BiK rating of between 9-17%.
Hybrid cars also cost £130 a year in road tax (VED), instead of the £140 charged for conventional models, and hybrid vehicles emitting less than 75g/km of CO2 can access the London Congestion Charge zone for free.
As hybrid technology has become more mainstream, the vehicles have also become affordable, costing a similar amount to an equivalent diesel. Hybrid powertrains are also offered in a wider variety of cars now than ever before, from superminis to luxury SUVs like the Range Rover Sport Hybrid.
Almost all hybrid cars have an automatic gearbox and are designed to be very quiet and smooth to drive, so they're typically relaxing and easy to master. Sitting in congestion, light controls and the lack of a clutch and gearlever can really reduce fatigue.
Hybrids also require very few changes to your driving habits, because they can be parked anywhere (you don’t need to find a charging point), refuelled at any petrol station and require the same level of care and maintenance as any ordinary car. A major hurdle for electric vehicles has been ‘range anxiety’, with early models often having a range of less than 100 miles and the need to find a working charging point to top up the batteries. A hybrid doesn’t need to be charged and can drive for hundreds of miles on a tank of fuel.
What are the cons of driving a hybrid car?
Once the traffic clears and you head out of town on faster roads, or on the motorway, hybrid cars rely on their petrol or diesel engines to sustain higher speeds. Because of this, hybrids lose their economy advantage in these conditions and will often use slightly more fuel than a modern diesel car.
Because of the small capacity of the battery packs fitted to hybrid models, they can’t travel very far, or for very long, on electric power alone – typically less than a mile. If you want to travel for a greater proportion of the time using just electricity, a plug-in hybrid model is more suitable, as most of these can be driven for 20-30 miles without the conventional engine kicking in. To achieve this, plug-in hybrids require a much larger battery pack that requires charging from a mains supply or public charging point, but they're also significantly more expensive to buy as a result.
Lastly, driving a hybrid car may not suit all drivers, particularly enthusiasts. With an automatic gearbox, engine and even eco-tyres all designed to save fuel, hybrid models aren’t going to appeal to devotees of hot hatchbacks or sports cars. However, times are changing, and hybrids are becoming far better to drive and much faster. A world where sports cars and even supercars are fitted with hybrid technology is already on our doorsteps.