Martin Winterkorn, 63, is to stay on another six years as chief executive of Volkswagen, Europe's biggest car maker said Sunday in Wolfsburg, according to dpa. The supervisory board has granted him a five-year extension after his current contract runs out at the end of this year, taking his term of office through to the end of 2016. He became CEO in early 2007. Observers said the long-expected move confirmed the trust that VW chairman Ferdinand Piech places in him. Winterkorn is a longtime associate of Piech, who is the strongman of the company as a former CEO, key shareholder and current chairman of the supervisory board. Both men are determined to expand the company in Asia and make it the world's biggest carmaker by 2018. Currently it trails Toyota and General Motors as number three. New factories in India, China and the United States are planned, and the group is expected to formally absorb sports car maker Porsche this year.