The tendency to produce electric vehicles has speeded up since 2000 as a result of researches into better engine performance to reduce greenhouse gas emissions, hence fuel consumption. For lower consumption, "assistance" for engines has appeared for electric motors, thus leading to the arrival of the first "hybrid" cars.
The Micro-hybrid (or Stop-Start) solution corresponds to the lowest level of hybridization. This concerns a reversible system that acts as a starter and alternator on a traditional car.
Micro-hybrid cars are traditional cars that are powered by an engine equipped with a Stop-Start function. The engine cuts off automatically when at a stop and is automatically triggered as soon as the driver starts up again. It helps decrease fuel consumption for city driving (stopping at a red light, traffic jam, etc.) of about 10% for urban usage, 6% in a standardised mixed cycle, and up to 16% in heavy traffic.
Parallel hybrid cars are the most widely known and widespread cars, mainly under the monumentum of the world's largest car manufacturer, Toyota.
As it is the case for the mild hybrid cars, an engine is coupled with an electric motor. The difference lies in the superior power of the electric motor which is able to power the vehicle alone, with the engine stopped, for short distances.
Parallel hybrid cars operate in an all-electric mode at start-up, at low speed, in traffic jams and when manoeuvring to park. This calls for a greater battery capacity than for the mild hybrid cars, as well as a rather particular transmission and high-performance management computer.
For the transmissions used on vehicles sold of the CVT (Continuous Variable Transmission) type, a device enables the motor to run in gear to deliver the ultimate performance.
Plug-in hybrid cars have evolved from parallel hybrid cars, and are equipped with batteries of a greater capacity. We speak of plug-in hybrids when a hybrid vehicle can be charged on an electrical network, which enables the use of an electric car for daily journeys.
Three factors are popelling plug-in hybrid cars to the forefront:
A substantial request on the part of users who are not satisfied with the performance of current hybrid cars.
A reduction in the price of batteries, an increase in performance, a demonstration of their reliability.
The arrival of major companies on the market, like General Motors with the Volt, Toyota with the plug-in Prius, Ford, VW and others.