Hybrid Synergy Drive® was created after Toyota engineers challenged themselves in the early 1990s to build a "21st-century car." The goal was to maximize fuel economy, minimize emissions and retain the "fun to drive" factor. Naturally, performance had to meet or exceed the competition.

The engineers were inspired by Toyota's worldwide Earth Charter. Established in 1992, the Earth Charter mandates environmental improvement throughout the company, from facilities to products. Reducing vehicle emissions and increasing mileage makes Hybrid Synergy Drive® the centerpiece of the program's success.

Increasing mileage without sacrificing performance is a big challenge. However, by as early as the 1960s, Toyota engineers had experimented with combining electric motors and gasoline engines for improved mileage. A high-efficiency, low-emission "Atkinson cycle" engine had been in development for several years, and Toyota was close to bringing an electric vehicle to commercial fleets.

It didn't take long for Toyota engineers to realize they had a head start on building a whole new type of powertrain. After considering more than one hundred different designs, the basic architecture of the Toyota Hybrid System (THS) was established-the precursor to Hybrid Synergy Drive®.

A clean break from the past
The engineers were adamant that the hybrid drivetrain be completely new, without trying to "re-purpose" an existing drivetrain. This approach was the best way to build for long-term sustainable development and refinement.

Hybrid Synergy Drive® has an electronically controlled variable transmission with a planetary gear set. It seamlessly accepts power from the gasoline engine and the electric motor. A high-voltage electric system powers the motor, and the advanced drivetrain is computer controlled for optimal power and efficiency.

Rapid progress
In December 1997, Prius debuted in Japan with Toyota's first commercial hybrid drivetrain, THS. In 2000, Prius entered the U.S. with a 58-hp engine and 40-hp motor. On October 17, 2003, the next-generation Prius engine and motor power increased to 76 hp and 67 hp. This was the premiere of Hybrid Synergy Drive®.

The big leap in power that occurred from THS to Hybrid Synergy Drive® continues. Highlander Hybrid, due in 2005, has a 3.3-liter V6 engine and two electric motors for a combined estimated 270 horsepower. Hybrid Synergy Dive® can be adapted to many types of cars, pickup trucks and SUVs on the road today.

Hybrid Synergy Drive® started as an idea-building a greener vehicle for the 21st century. Numerous automotive industry awards and great market success prove the power of this idea. As one Hybrid Synergy Drive® engineer says, "I believe my job is to make the dream a reality."