Automobiles of the future must increase both environmental and safety performance, while significantly increasing the all-important motor vehicle characteristic of being fun to drive. To achieve superior driving performance, which is the basis for driving enjoyment, the conventional approach has been to increase output and torque by increasing engine displacement or using supercharging. However, this approach decreases fuel efficiency, making it difficult to achieve compatibility of environmental performance and power. In other words, fuel efficiency and power are in a trade-off relationship. By using the Toyota Hybrid System (THS), the Prius was able to escape the inevitability of this relationship in a paradigm shift. The goal of the Hybrid Synergy Drive concept is to achieve compatibility of high levels of both environmental performance and power.The newly developed hybrid system, THS II, targets both greater power and improved motor power transmission efficiency, advancing energy management control for the entire vehicle. As a result, Hybrid Synergy Drive has been developed, which markedly increases power performance, improves acceleration performance, and at the same time achieves the highest degree of environmental performance in the world.


Automobile hybrid systems combine two motive power sources, such as an internal combustion engine and an electric motor, to take advantage of the benefits provided by these power sources while compensating for each other's shortcomings, resulting in highly efficient driving performance. Although hybrid systems use an electric motor, they do not require external charging, as do electric vehicles.
Characteristics of Hybrid Systems
Hybrid systems possess the following four characteristics:

1) Energy-loss reduction
The system automatically stops the idling of the engine (idling stop), thus reducing the energy that would normally be wasted.

2) Energy recovery and reuse
The energy that would normally be wasted as heat during deceleration and braking is recovered as electrical energy, which is then used to power the starter and the electric motor.

3) Motor assist
The electric motor assists the engine during acceleration.

4) High-efficiency operation control
The system maximizes the vehicle's overall efficiency by using the electric motor to run the vehicle under operating conditions in which the engine's efficiency is low and by generating electricity under operating conditions in which the engine's efficiency is high.

The series/parallel hybrid system has all of these characteristics and therefore provides both superior fuel efficiency and driving performance.