How does a hybrid car work?

014 Apr 2024

This guide will get you clued up on mild hybrids, full hybrids and plug-in hybrids

With over a million electric vehicles now registered in the UK, EV uptake continues to point upwards. Hybrids, with their combined electric motors and internal combustion engines, continue to be a popular choice for many first-time EV buyers, too. With a hybrid, those who are less confident about fully transitioning to an EV can get used to driving with electrical energy, with fuel to fall back on as needed.

So without further ado, let’s take a closer look at the three types of hybrid car available: mild hybrid, full hybrid and plug-in hybrid.

Mild hybrids

Peer inside a mild hybrid and you’ll find a small electric motor working together with a combustion engine. Neither of them can be used without the other – the electric motor depends on the combustion engine and vice versa. The engine is powered by the small electric motor.

Using a belt alternator starter (BAS) system, a mild hybrid car generates energy through braking (regenerative braking if you want the official term). This means the kinetic energy from a car’s momentum is converted into electricity to be stored in its batteries. Clever, right? Drivers can take advantage of BAS energy generation while coasting, as well as while stopping at a light, when the engine automatically turns off to save fuel.

Plug in or refuel: You refuel a mild hybrid the same way you would a regular non-EV car. A mild hybrid doesn’t have an external charger port, and the battery self-charges, so you can’t plug it in even if you wanted to.

Best for: Those on smaller budgets. Mild hybrids are a good entry-level option, offering a modest amount of power and some efficiency gains.

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Full hybrids

The most common choice of hybrid, like it’s mild sibling, the full hybrid also houses a combustion engine and small electric motor. But unlike the mild version, these can work together or independently of each other.

Thanks to the electric motor’s position within the drivetrain, you can drive a full hybrid in electric-only mode, at low speeds and for short distances. Once you reach a certain speed, the combustion engine will kick in and work alongside the electric motor to power you, fuel-efficiently, on your way.

It’s worth noting that even if you’re cruising around town in EV mode, the combustion engine is generating all that lovely electricity by burning fuel. It sounds counter-intuitive, but this means that your full hybrid is actually most efficient when the combustion engine and electric motor work together, rather than separately.

Plug in or refuel: Like the mild hybrid, there’s no need to set foot near a plug. There’s no charger port and the battery self-charges. Which is nice.

Best for: Those with range anxiety. The engine is always there to zap the small battery back up to full capacity, so long-distance drivers need not worry about running out of juice. Even with a flat battery, you can always rely on petrol or diesel alone.

Plug-in hybrids

Plug-in hybrids are one step closer to going fully EV. With bigger batteries that you charge by plugging into an external power source, you’ll be able to travel much further on electricity alone than you would in a full hybrid.

Obviously driving a car with a bigger battery means you’re carrying a heavier load than a typical petrol or diesel car would. On the plus side, if you always charge up overnight and don’t drive more than 30 miles a day, in theory you wouldn’t need to pay for petrol again. Still, the combustion engine is always there if the battery runs out of juice and will roar into life like a typical petrol or diesel vehicle.

Plug in or refuel: As you might expect, you can plug in this hybrid using a wall box at your home, or a public charging point like you would with a fully electric car. With a combustion engine included, of course you can also refuel with petrol as needed, too.

Best for: Those with short commutes who want the EV experience. Depending how far you typically travel, you may never need to refuel with petrol. But the option is always there if you do ever drive further afield and need to refuel the combustion engine.

Hopefully this short guide to hybrids has given you some food for thought. If you’re currently driving, or considering a hybrid, check out our Fuel & Charge card. It gives you access to premium fuel and EV chargers in the UK and across Europe.

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