Controllers
Major changes to the PCU (Primary control Unit) which take the electricity and either puts it in the battery, uses it for propulsion or stores it for future use has had a 36% weight reduction and decreased its size by 37%. Improved cooling and ventilation allow for an operating voltage increase to 650 Volts from 550 Volts.

The battery pack has undergone change as well, just not as radical as with the PCU. The new storage battery uses the same chemistry and slightly different packaging. These changes improve cooling and by keeping the battery at a more even temperature, power output has increased slightly.

The Tri-mode power feature enables drivers to customize the operation of the hybrid power system.

Driver Involvement
Rather than just put a display on the dash that tells occupants what the Synergy Drive system is doing, Toyota has chosen to involve the driver by providing three modes of operation.

EV mode is the one that allows the driver when conditions are right to remain in electric mode longer. Engine start up is limited and the driver may go a limited distance on electricity.

Power Mode is the "performance" mode that improves throttle response and provides a sportier feel to driving.

Eco mode is the most versatile and maximizes fuel economy across all driving ranges. Air conditioning is minimized, throttle response is smoothed out (slight decrease) and ironically, performance in low traction situations such as ice/snow improves.

Conclusion
Satoshi Ogiso, Chief Engineer, Toyota Motor Corporation had a team of roughly 2000 engineers going over every aspect of the Vehicle. His team took advantage of weight reductions of components, improved operation and vehicle design. All aspects of the vehicle were looked at because fuel economy is a total vehicle issue and not just restricted to power train components. That is what Synergy is all about.


Photo Credit : Toyota