What’s the difference between hybrid, plug-in hybrid and EV?

Every car on the road today has a battery and an electric motor, even the oldest petrol-powered gas guzzler.

They need electricity to run ancillary systems like the headlights, wipers and audio system and have an electric motor bolted to the side of the engine (which is often referred to as a starter motor) that helps fire it into life when you turn the key.

But hybrids and battery-electric cars go a step further, using electricity to help propel the vehicle.

And just as there are different types of combustion engines – petrol and diesel, four-cylinder and V8, boxer and rotary… the list goes on – there are numerous variations on hybrid and electric car configurations.

Hybrid vehicles have been around in the mainstream for more than 25 years now, popularised and pioneered by the Toyota Prius, and now offered by a wide variety of brands on a broad range of models, from small city runabouts to family SUVs, luxury sedans and even a select number of sports cars.

Fully-electric cars are also not a new concept, but have become a silver bullet to reducing pollution in the past decade and advances in battery technology have made them a more viable long-term option.

So, here’s a brief rundown on the differences between them all, and the advantages and disadvantages in each configuration.

This is the most basic of hybrid set-ups and essentially uses an upgraded version of existing hardware to allow the engine to temporarily shut down when the vehicle is stationary or coasting at freeway speeds to save an incremental amount of fuel.

The system operates automatically, with the 12V battery maintaining power to all the necessary systems while a computer determines when the engine is reignited – either because the voltage has dropped or the driver has engaged the clutch pedal (in a manual) or released the brake pedal (in an automatic) as an indication the vehicle is required to accelerate again.

More powerful mild-hybrid systems are also becoming more prevalent, typically integrating a 48-volt electric motor/generator which is designed to improve acceleration as well as reduce fuel consumption.

Positives
+ Simple
+ Cost-effective
+ Incremental reduction in fuel consumption

Drawbacks
- Can be annoying in heavy traffic
- Accelerates wear on battery and starter motor
- Will not realise huge improvements in economy

The most common form of petrol-electric powertrain is what is termed as a parallel hybrid, where a combustion engine is teamed with an electric motor to improve performance and reduce fuel consumption.

In this layout, either the petrol engine or electric motor can individually provide motive force to propel the vehicle, or both sources combine to increase acceleration.

In most cases, the petrol engine has a lower capacity than normal and/or a lean-burning combustion cycle to be as efficient as possible.

The battery pack is typically smaller than in a plug-in hybrid or fully-electric car, offering a limited driving range on electric power alone. It can only be replenished through regenerative braking when the vehicle decelerates.

As the name suggests, the electric motor operates in tandem with the petrol engine to deliver its added torque through the same transmission.

Positives
+ Wide range of options
+ Decent fuel economy savings
+ Affordable technology

Drawbacks
- Limited electric-only driving range
- Still uses fuel for the majority of driving
- Compromised packaging and space

A plug-in hybrid electric vehicle (PHEV) operates in much the same way as a conventional hybrid car but adds more electric-only driving range.

In the majority of cases, it links a petrol engine and electric motor together in the same way. But the electric motor is generally more powerful, the battery is larger and, as the title indicates, it can be plugged-in to recharge.

As such, some plug-in hybrids can provide up to 80km of range on electric power alone at speeds of up to 120km/h, meaning owners can usually complete an average daily commute without using any petrol and still have the ability to travel long distances.

Positives
+ Extended electric-only driving range
+ Significant fuel consumption reduction
+ Improved acceleration

Drawbacks
- Limited choice
- Compromised packaging and space
- Significant weight increase

An electric vehicle (EV) does not have a petrol engine at all and runs entirely on electricity.

Most EVs have a large-capacity battery pack that provides adequate driving range and either one or two electric motors with comparable performance to a conventional vehicle.

Obviously, an electric car can only be refuelled by plugging it into a power source, either a regular domestic power point (or a purpose-built home charger) or a higher-voltage public charging station. But it takes longer to recharge a battery than it does to refuel a petrol tank.

Although electric cars cost significantly more than a conventional vehicle at the moment, they are cheaper to run with lower costs to ‘refuel’ and maintain.

Positives
+ Zero emissions
+ Improved interior packaging
+ Reduced running costs

Drawbacks
- Expensive
- Longer refuelling time
- Limited public charging network

The final configuration in the electric car landscape is probably the most complicated and expensive but one that ultimately could be the best solution.

Fuel-cell electric vehicles (FCEVs) have been under development for decades, and only now are beginning to become a commercial reality with companies such as Toyota and Hyundai bringing FCEV models (in extremely limited numbers) to the road.

A fuel-cell vehicle is an electric car, but instead of having a battery pack it features an on-board power station that generates electricity via a chemical reaction when its elements are delivered compressed hydrogen.

As hydrogen is one of the most abundant elements it is considered a highly sustainable fuel source and the only by-product from the fuel cell is water vapour.

It is stored in pressurised tanks within the vehicle, which can be replenished in roughly the same time as it takes to refuel a petrol-engined car, and can deliver a longer driving range than a battery-electric car.

Positives
+ Longer driving range
+ Sustainable fuel source
+ Quicker refuelling

Drawbacks
- Not yet available for wide-scale public sale
- No commercial refuelling network
- Extremely limited choice