Porsche has a lot to thank Holger Härter for. The slightly scruffy 51-year-old, nearly always seen with stubble, hardly seems the type to be chief financial officer of one of the world's most prominent and successful family-run companies.

But Mr Härter has run the German sports carmaker in ways that are very un-family-like. In the same way that secretive traders in Connecticut or London have built up powerful hedge funds, so this trained economist from rural Germany has carved out a niche for himself as a financial wizard sitting in Stuttgart.