Nissan said its first hybrid model will nearly double the mileage of its petrol-engined equivalent, while keeping costs down with a simple, single motor system.

The company is launching a petrol-electric Infiniti M sedan, called Fuga in Japan, late this year. Nissan said its one motor, two clutch system would achieve far better fuel economy, at a much lower technical cost compared with hybrid leader Toyota's complex, two motor "series parallel" system.

Nissan has been using Toyota technology in its only hybrid model to date, the US-built Altima.

Koichi Hayasaki, chief engineer of Nissan's rear wheel drive hybrid system, said: "Typically, carmakers say the fuel economy improvement on their cars using a 'strong' or 'full' hybrid system is roughly 30%, while for 'mild' hybrids it's 15%.

"We're aiming for an improvement of 60 to 90%," he said during a presentation at the company’s Yokohama headquarters.

Nissan's hybrid system is similar to that of Volkswagen’s, using an extra clutch that separates the electric motor from the engine to allow for driving using only electric power when the battery is charged.

Hayasaki said Nissan's system enables it to better control the motor by using a lithium-ion battery instead of nickel-metal hydride, which is slower in capturing and discharging energy. Using a lithium-ion battery, he said, eliminates the need for a torque converter.

The system took six years to develop in house and, together with more accurate electronic controls, it allows the engine to idle more frequently and therefore use less fuel. Also, by having fewer components, Hayasaki said, Nissan's hybrid system was roughly 30kg lighter than Toyota's series parallel system.

As part of its drive to reduce carbon dioxide emissions from its cars, Nissan is also planning to also launch fuel-efficient three- and for-cylinder petrol engines and stop/start technology during this business year.

The new March (Micra), due for launch in Japan this month, will be the first to use the stop/start feature while Nissan is due to mass-market its Leaf electric car starting in December.