
The name was changed in anticipation of its use in vehicles outside the Toyota brand ( Lexus the HSD-derived systems used in Lexus vehicles have been termed Lexus Hybrid Drive), was implemented in the 2006 Camry and Highlander, and would eventually be implemented in the 2010 "third generation" Prius, and the 2012 Prius c. The second generation system first appeared on the redesigned Prius in 2004.

HSD is a refinement of the original Toyota Hybrid System ( THS) used in the 1997 to 2003 Toyota Prius. The Synergy Drive is a drive-by-wire system with no direct mechanical connection between the engine and the engine controls: both the gas pedal/accelerator and the gearshift lever in an HSD car merely send electrical signals to a control computer. The HSD also combines an electric drive and a planetary gearset which performs similarly to a continuously variable transmission. HSD technology produces a full hybrid vehicle which allows the car to run on the electric motor only, as opposed to most other brand hybrids which cannot and are considered mild hybrids. offers similar hybrid transmissions to other car companies. Previously, Toyota also licensed its HSD technology to Nissan for use in its Nissan Altima Hybrid. First introduced on the Prius, the technology is an option on several other Toyota and Lexus vehicles and has been adapted for the electric drive system of the hydrogen-powered Mirai, and for a plug-in hybrid version of the Prius.

Hybrid Synergy Drive ( HSD), also known as Toyota Hybrid System II, is the brand name of Toyota Motor Corporation for the hybrid car drive train technology used in vehicles with the Toyota and Lexus marques.
