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Surprisingly, the first Toyota hybrid vehicle ever displayed was a two-seat sports car shown at the 1977 Tokyo Motor Show. It was a Japanese-market Sport 800 with the engine and transmission replaced by a gas turbine and an electric motor! Gas turbines are similar to the turbofan engines that power jet aircraft. They burn fuel in a combustion chamber that causes a blade-covered shaft to turn at high speed. Toyota had been working on turbine hybrids since 1965, and experiments continued into the 1980s.
The Sport 800's turbine did not power the wheels directly. Instead, the shaft turned an electric generator that both charged onboard hybrid batteries and powered an electric motor connected to the rear wheels through a conventional differential and axle. This type of configuration is used today in some heavy-duty buses and trucks, and is called a "series" hybrid.
In the 1960s, several of the world's automakers explored the application of turbine engines to automobiles. In fact, a turbine-powered racecar nearly won the 1967 Indianapolis 500®, dropping out four laps before the finish. Unlike Toyota's approach, these other makers' turbine engines powered the wheels through a mechanical transmission.
Toyota's first production hybrid vehicle entered the Japanese market in 1997. The 24-passenger Coaster Hybrid bus featured a gasoline engine running the generator in a series configuration, similar to the Sport 800 system described above.
A few years earlier, Toyota began a new hybrid program that paved the way for Prius, Hybrid Synergy Drive® and Highlander Hybrid. In 1994, Toyota embarked on a development program for a "21st-Century vehicle," with Toyota's environmental Earth Charter as the inspiration for high efficiency and low emissions. Engineers settled on a hybrid solution based on more than 30 years of Toyota hybrid heritage. After the decision was made to move forward on a hybrid system, more than 100 different configurations were considered.
Toyota displayed an early Prius concept in 1995 with powertrain elements that would appear in the production Prius: energy-recovering "regenerative" braking, engine shutoff when the car is stopped, computer controls and a continuously variable transmission. Some of the notable differences between this powertrain -- the Toyota EMS (Energy Management System) -- and later Toyota hybrid powertrains were its belt-driven rather than gear-based continuously variable transmission, and its use of a capacitor instead of hybrid batteries to store energy. This configuration, in which both the gasoline engine and the electric motor power the wheels independently or together, is called a "full hybrid."
The first production Prius appeared in Japan in 1997 with a new THS (Toyota Hybrid System) full hybrid powertrain. Prius with THS debuted in American showrooms in 2000. The second-generation Prius that we know today arrived in 2003, and was the first vehicle with Hybrid Synergy Drive®. The rest, as they say, is automotive history.
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