Who is going to buy a V8 that is probably slower and less fuel efficient than a V6 turbo?

Sorry but the days of the N/A V8 are over. Also having V8 in current turbo models only will help Porsche justify the huge premium it charges to go from the S to the turbo. Lastly all the competition is going V6 turbo int heir mid range models, it makes it easier for costumers to accept it.

One more killer argument: 6 cylinder is good enough for their most sporty car, the 911. So why not for the Panamera and Cayenne?