Porsche is prepared to guarantee the position of Ferdinand Piëch, one of its largest shareholders, as supervisory board chairman of Volks-wagen as the corporate governance battle at Europe's largest carmaker turns increasingly bitter.

A total of 80 per cent of investors present at an annual or extraordinary shareholders' meeting at VW would be needed to vote out Mr Piëch, according to the carmaker's articles of association, and Porsche, the largest shareholder with 18.5 per cent, would be able to block any resolution as turnout is never 100 per cent. There is a sense at Porsche and VW that a boardroom struggle over Mr Piëch's role is in danger of getting out of control to the detriment of all sides.