Tweedy Browne, the influential US activist fund manager, is so concerned by the state of corporate governance at carmaker Volkswagen that it is considering scrapping or scaling back its investments in Germany.

The fund manager, which has $13bn of assets under management and has pushed through change at several companies - including Conrad Black's Hollinger - has started talking to other VW shareholders to mobilise them to try to force out the carmaker's controversial non-executive chairman, Ferdinand Piëch.