FRANKFURT (Reuters) - Volkswagen boss Herbert Diess said he sees no need for action when asked about a potential listing of the group’s Porsche luxury division, adding the unit’s cash flow was key to Volkswagen’s turnaround. “That’s why you need to think very very hard about every single step,” Diess said at the group’s annual press conference, adding it was the carmaker’s aim to fund its strategic shift via cash flows from existing businesses. People familiar with the matter told Reuters last month that Volkswagen was considering a listing of Porsche AG to rake in cash needed for the group’s shift towards software and electric vehicles.