Can anyone tell me if the GPS navigation system console can be added by the dealer or is it strictly a factory option?

By the way, I'm using the Cayenne S to tow a 5000 pound trailer and it's a FANTASTIC tow vehicle. The brake controller is integrated into the vehicle computer, so all you have to do is attach the trailer wiring harness (and the hitch) and off you go. There's no need for an outboard brake controller (I was concerned about drilling holes in the dash until I found out that one wasn't needed).