Nissan said today that its chief executive Carlos Ghosn will step aside from the post after leading the firm for 16 years.

The move will allow him to concentrate on deploying his cost-cutting expertise across its alliance with Renault and newly added Mitsubishi Motors. 

In handing over the helm to Hiroto Saikawa, Ghosn ends years of speculation over when he would relinquish the top job at Japan's second biggest car maker.

This comes amid investor concerns that he was stretching himself too thin. 

The change in leadership is aimed at making the best use of the greater scale that Mitsubishi brings to lower costs at a time when automakers are under pressure to expand and compete in new technologies such as self-driving cars. 

Known as 'Le Cost Killer' from his earlier career at Renault, Ghosn boosted his reputation by engineering Nissan's comeback from years of losses and debt.  

Unafraid to trample over long-standing business customs, he became a hero in Japan and one of the auto industry's best known executives. 

Ghosn, 62, will continue to be chairman at Nissan, a position he also holds at Renault and Mitsubishi. He also leaves in his place a man cut from very similar cloth.

Saikawa is a veteran cost-cutter with much of his career spent in managing purchasing and supply chains. 

The 63-year old was named the company's chief competitive officer in 2013, became co-CEO last November and also currently heads Japan's auto industry lobby.

Ghosn began his career at Michelin in France, moving on to Renault, where he oversaw a turnaround of the car maker. 

He joined Nissan in 1999 after Renault bought a controlling stake and became its CEO in 2001. 

Nissan is the strongest of car makers in the alliance, long outperforming Renault in terms of vehicle sales and profits, while Mitsubishi still needs an overhaul after a mileage cheating scandal last year. 

Bringing Mitsubishi into the fold has put the three-way alliance on par with Toyota and Volkswagen - all producing around 10 million vehicles annually.