I have a 2008 Cayenne 6 speed with the same engine with 160k miles. I disregarded the C30 recommendation and have used an A40 oil with 10k change intervals (Mobil 1 0w-40, but probably Castrol 0w-40 next change since Amazon has been shipping it for $22 for a 5 quart jug). I have not done a UOA, but at 160k miles, I still burn no oil between changes.
I should note that if I was less lazy, I would have no problem using a C30 oil, but with M1 or Castrol 0w-40, I only have to keep one oil for all my vehicles.