Yamaha Motor Co. has completed a prototype of what it hopes will be the world's first gas-electric hybrid motorcycle, company sources said Thursday.

The Hybrid Commuter, equipped with an electric motor and gasoline engine, achieves mileage of 250 km per liter, making it much more fuel efficient than regular motorcycles, they said.

Japanese hybrid cars have already hit the market. Toyota Motor Corp. and Honda Motor Co. -- the only two automakers in the world that sell hybrid cars -- launched their models in the late 1990s.

Japanese automakers are enthusiastic about developing hybrid vehicles, which boast greater fuel efficiency and are more environmentally friendly than conventional gas-only cars because their exhaust contains less harmful substances.

According to the Yamaha sources, the mileage of the Hybrid Commuter is more than 100 km per liter higher than the 146 achieved by Honda's Super Cub 50 Custom, currently regarded as the world's most fuel-efficient motorcycle.

The Hybrid Commuter has a bicyclelike frame and is 185 cm long and 113 cm high.

The motorcycle uses an electric motor installed in the pedals to start up and then switches to the small gas engine placed under the saddle when the speed reaches 5 kph.