@AudiTT:
jup, you´re right. At least for the 911 and Boxter with the flat six. The other models share much and more with Audi and VW, not only a switch here and an engine there.
In the Cayenne not one engine is from Porsche. And in the Panamera, too, afaik.
And the Cayenne´s chassis is shared, also the drivetrain.
I just wanted to correct your first statement

Not whole Porsche is that special as many of us wishes it to be (me included).
The only "special" brands in the VAG (that doesn´t exist anymore, btw., it´s only VW Group now) are Bentley and Bugatti.