Self-charging hybrids – What are they and do you need one?

It’s an odd term, self-charging hybrid. A term thought up by Toyota to advertise its hybrid cars, it seems almost too good to be true. After all, you don’t get self-filling petrol or diesel cars or an electric car that charges itself, do you? Even so, there is truth to the term. They do have a battery that is charged as you drive.

In this guide, we’ll explain what they are and how you could benefit from a hybrid. Don’t think this guide is just suitable for new cars, either. We’ve seen two decades of hybrids now, so many used cars for sale in the UK will likely be some sort of hybrid.

What is a self-charging hybrid?

Also known as a full hybrid, a self-charging hybrid can run on electricity alone but doesn’t have any way to top it up from the mains. As electricity is produced via regenerative braking or via the engine, battery sizes are small, so you’ll only get a mile or two from a full pack before the engine kicks in.

However, the electric motor can also assist the engine under acceleration to lighten the load, improving efficiency. The battery pack can also run the air conditioning and other functions, meaning the engine can stay off for longer when you’re stationary or if you lift off the throttle.

They’re not to be confused with mild hybrids. Although these also charge without being plugged in, their effect is a lot more, well, mild. Most only allow extended periods of engine off time, either when you’re stationary or coasting on the motorway although some now have short periods of electric running at low speeds.

What are the benefits?

There’s a good reason all those Ubers are Priuses, a good self-charging hybrid is unbelievably efficient around town and in stop-start traffic. They’re able to charge their batteries as you slow for the inevitable red light or traffic jam, while a slow creep forward maximises electric running.

Expect economy north of 60mpg for the smallest, most efficient self-charging hybrids around town if you drive carefully. Larger self-charging hybrids won’t do quite as well but should outperform pure petrol and diesel rivals.

Naturally, with the engine switched off for good chunks of the journey, your CO2 emissions will also be significantly lower. This is good for air quality and also lowers company car tax. Some second-hand cars may even offer low or free road tax. You can check the DVLA website to see what cars benefit from this.

Any downsides?

Long distance economy certainly won’t be bad, but diesel is still the best option here. While a self-charging hybrid might manage mpg in the 40s or 50s at motorway speeds, the most frugal diesels might do over 60 or even 70mpg.

Keen drivers are unlikely to warm to the automatic gearboxes attached to most hybrid cars. In many cases they don’t have conventional gears, so you don’t have much control of what’s going on while the engine can be held at constant high revs when acceleration.