I've got a 2010 MY11 2.7l D4 and also leave behind clouds of gray smoke under heavy acceleration. I have only done 12k. I mentioned it to the dealer on both the 5k checkup and 12k service. They also said it is normal. It has done it since day one. Our car doesn't go through oil either. I have noticed quite a number of D4 TDV6 doing the same thing.

