Volkswagen is to pay ?3.3 billion ($4.7B) for a 42 percent stake in Porsche’s main production division, the two German carmakers said yesterday as they thrashed out more details of a move towards a full integration. In a move that will amount to a rescue of debt-laden Porsche, VW will also buy the automobile trading business of Porsche Holding Salzburg, Europe’s biggest vehicle dealer that is also owned by the sports car maker’s family owners.