In car speak, hybrid refers to the use of more than one type of technology to provide motion. Typically, this means an internal combustion engine and an electric motor that can power the vehicle alone, or assist the internal combustion engine. 

Hybrid vehicles typically use less fuel and produce fewer emissions than a similar sized conventional vehicle.

This is achieved by:
  • Capturing energy that would normally be wasted during braking and deceleration 
  • Storing this captured energy in special battery packs 
  • Reusing this energy to assist the internal combustion engine, or using the electric motor alone for low speed driving 
  • Stopping the internal combustion engine when it isn’t needed 
  • Using smaller, more fuel-efficient internal combustion engines than would otherwise be used in a similar sized conventional vehicle 

The common types of hybrid vehicle systems 

The first type uses an electric motor to assist a small petrol engine to drive the vehicle. The electric motor changes to a generator during braking, deceleration, and light cruise conditions. The energy produced is stored in a battery pack, and is then used to assist the petrol engine accelerate the vehicle when needed. This type cannot be driven on the electric motor alone.

The second type also has both electric motors and an internal combustion engine. Again, the electric motors can be used to generate power, which is stored in battery packs. Either the internal combustion engine or electric motor can power the vehicle independently of each other. However, the electric motor is generally only capable of low speeds and relatively short distances. The electric motor can also assist the internal combustion engine.

Plug in Hybrid

Another variation on the hybrid theme is the plug in hybrid. These operate in a similar way to those already mentioned, however their battery packs can also be charged from mains power. Benefits include the ability to recharge during off peak periods to reduce operating costs.

Mild hybrids

These are conventional vehicles that generate and store electricity during braking and deceleration so that it can be used later to drive electrical equipment, reducing fuel consumption.

Range Extended Electric Vehicles

Another system, sometimes called a range extended electric vehicle, uses a full electric drivetrain and battery pack which is supplemented by a petrol engine driving a generator.  There is some debate over whether these should be regarded as a true hybrid vehicle though.

Getting the best from a hybrid

Hybrid vehicles are at their best in city traffic where there is a lot of stop / start driving to charge the battery pack. Highway driving does not provide as many free opportunities to recharge the battery packs. 

Depending on traffic conditions and how the vehicle is used, significant fuel savings can be achieved. However, their highway fuel consumption can probably be equalled, if not bettered, by some modern turbo diesels.

Disadvantages

Due to the cost of the technology, hybrid vehicles are more expensive than an equivalent conventional model.

Battery life

Battery life is currently an unknown quantity as hybrids have not been available in Australia for any significant length of time. However, hybrid manufacturers generally offer a longer warranty on the battery packs than is offered on the rest of the vehicle.

Safety 

Hybrid and electric vehicles are required to meet all current vehicle safety standards and some additional electrical safety standards.  However, like any piece of electrical equipment, there is a risk of electrocution if safety precautions are not followed.