Sure, it was the Prius that made Hybrid engines popular, but Toyota were actually working on hybrid technology long before that. Their first hybrid engine, the Gas Turbine Hybrid, started development back in 1965. It took 12 years, but the engine eventually made it into a prototype Toyota Sports 800, which was shown off at the Tokyo Motor Show in 1977. It had a 22kW engine with a 2-speed transmission.
Considering the first-gen Prius was launched in 1997 in Japan, that's one hell of a long journey for hybrid engines to make it into a mainstream car. It does make you think about the long-term possibilities for alternative car fuels, doesn't it?