So, Autocar has given more info and a (Mercedes PR) video clip on the G500 4x4²!
(This first bit is based on info we got first, about there being two clutch packs in the rear and torque vectoring, read below from the EDIT onwards for the updated theory following info that there will probably be one clutch pack to send power rearwards and one for the rear diff:)
http://youtu.be/CcNo07Xp8aQMagnussen just posted some songs about how he feels about the news:
I've never seen it done in any car test before: Matthias Malmedie from Grip was doing the usual review of the new Merc AMG model, driving around San Francisco and then heading towards Laguna Seca. But then he spotted a Porsche dealership on the way, put on a devilish grin, and did a U-turn in order to pull up right at…