Honda Motor Co. has unveiled a new motor-assisted driving system that will drastically improve fuel efficiency and reduce carbon dioxide emissions.

The new hybrid system, called the Honda Integrated Motor Assist, enables a car with a 1-liter gasoline engine to run 30 km per liter, Honda said. Currently, cars with a regular 1-liter gasoline engine only run about 15 km per liter. The automaker said it plans to launch passenger cars with the hybrid engine next year.

The new system has a thin motor between the engine and the transmission, which assists the driving force when the driver accelerates. As the vehicle slows down, the driving energy is converted into electricity and stored in a device called an ultra capacitor, the company said.

With the new system, Honda officials said, a vehicle with a 1-liter engine will have a driving power equivalent to a regular car with 1.5-liter gasoline engine. The engine also produces less carbon dioxide and nitrogen oxide emissions than conventional counterparts, it said. But Honda has not yet quantified the emission cuts.