Why?! When there is a Unimog?
AFAIK this one is based on Unimog technology (axles etc.). It started life as a purpose-built vehicle for the Australian army who seemed to have wanted a vehicle that can transport heavy loads and still has enough traction on loose terrain.
http://www.auto-motor-und-sport.de/news/mercedes-g-klasse-6x6-1333137.html
One can't really blame Mercedes that they realized it would make a perfect toy for Sheiks to play in the desert. Maybe Schwarzenegger will buy one, too. But he actually already has a Unimog.