There's never been any doubt about the industrial and financial heft of the Porsche and Piëch families. Their dynasty, descended from the son and daughter of protean engineer-executive Ferdinand Porsche, controls Europe's most profitable car maker and its largest independent vehicle-distribution company. Between Porsche cars in Stuttgart and Porsche Holding in Salzburg the family has the means to do pretty much what it wants. Nevertheless its decision to acquire a 20-percent share of Volkswagen, Germany's largest car company, came as a shock, writes Karl Ludvigsen.