Its a smart move by Porsche b/c in other parts of the world, namely Europe right now, Cayenne sales haven't been spectacular because the cost of fuel is so high. A V6 version makes sense for those markets because Porsche can still make a load of profit moving more models and gain through economies of scale. It doesn't hurt either that the 3.2L engine is a production engine widely used by VW/Audi's performance models.