Volkswagen Group chief executive Martin Winterkorn has told senior staff that he would present a new structure for the company by October at the latest, according to the German business magazine magazine Automobilwoche.

The magazine quoted Winterkorn telling senior staff late last week that "it is time to further develop our management model and reorganise structures and duties. We have to become faster, more efficient and more flexible."

Volkswagen Group is aiming to be the world's largest car company by 2018, but some analysts and investors worry that the company's profitability is held back by a high cost base.