See all Motoring AdviceThere are big changes coming in the new-car market, with most manufacturers turning to electrification for their next generation of models. But in the eyes of many buyers, one of the big hurdles to making the switch to a fully electric car is range anxiety - the fear that an EV won't get you to your destination as easily as a petrol or diesel car can.
It's true that a fully charged battery won't get you as far as a tankful of fuel in most instances, so car makers are making the transition to full electrification easier with the introduction of hybrid models. As the name suggests, these cars offer petrol or diesel power, but with an element of electrification to help reduce emissions in everyday driving.
They're not the zero-emissions solution that an EV offers, but the boost in efficiency should be welcomed, especially because many of these systems help petrol models to deliver the kind of efficiency that was once only available with a diesel-powered car. These petrol hybrid models should deliver lower everyday running costs.
Hybrids have their benefits, but there are different hybrid systems that deliver varying degrees of electrical assistance. Here we break down the four main hybrid drive configurations to help you pick the system that works best for your needs.
Mild hybrid
The most basic level of hybrid assistance is the mild-hybrid system. This set-up is useful because it can be added to existing petrol or diesel powertrains by car makers without too much effort - the hardest part is trying to physically fit the system into the car. It's a simple way to make a drive system more efficient without compromising the way a car drives.
The most common set-ups use a more substantial electrical system than a standard car’s, with the capability to provide power for the car's systems when the engine isn't running. This means the stop-start system activates more often (sometimes when the car is coasting), while the electrical system also sometimes provides assistance when accelerating. However, while the small electric motor will assist the engine, at no point will the car be able to run on electric power alone. Mild-hybrid systems are usually found on cars with automatic gearboxes, although manual models can be had with such systems, too.
Full hybrid
The Toyota Prius was the car that really pioneered the full hybrid system. This set-up features an engine, electric motor and battery pack, while the car's automatic gearbox is designed to manage power between these three elements and the wheels. The system is fully automatic, so driving a full hybrid is as easy as driving any auto-equipped car.
Toyota has used the phrase 'self-charging hybrid' to describe its hybrid drive system. This refers to the fact that decelerating and braking harvests energy back into the battery for later use by the electric motor. Unlike mild hybrids, full hybrids can run on electric power alone, but only for very short distances. Full hybrids offer lower emissions than conventional petrol or diesel models, but are at their most efficient at lower speeds - the faster you go, the more they rely on the combustion engine for drive.
Plug-in hybrid
A plug-in hybrid electric vehicle, or PHEV, is a development of the full hybrid. Here you'll find a similar engine and electric motor set-up, but a far larger battery will be included. This battery can be recharged on the move via braking (some PHEVs also offer recharging with the engine, although this isn't very efficient), but there is also a plug socket, so the battery can be recharged when the car is parked, just like a full EV.
PHEVs have even lower emissions than full hybrids, because they can travel further on electricity alone. The best examples offer over 100 kilometres of range, which could be enough for a day of driving, so as a result you could go for weeks without having to fill up with fuel.
Range-extending hybrid
A range-extending hybrid is similar to a PHEV, but it's the electric motor alone that drives the car's wheels, while the combustion engine is included to either recharge the car's battery or power the electric motor directly.
One car that was offered as a range-extender was the BMW i3 city car. The i3 REx - as it was known - had the same battery and electric motor as the all-electric i3, but it also featured a two-cylinder petrol engine and a small fuel tank that was designed to be a backup for when the battery ran out of energy. However, this system was designed to help get the car to a charge point, rather than being used for long-distance driving. Once BMW fitted a larger battery to the i3 for a longer range, the REx model was discontinued.