Not the off-road version but the std. GL, is this just a regular all wheel drive or is a little smarter .. Lets say 3 of the wheels are on ice, could the 4th wheel with good traction pull the truck out of trouble ?

 

Yes.......

I have the off-road version and the only additional benefits ( beyond the adaptive suspension ) I get are being able to lift the vehicle to a higher clearance AND lock the center and rear differntials which would benefit anyone contemplating extreme mud or snow situtions ( which I occaisionally encounter )

The standard 4 matic of MB allows the vehicle to send power to a single wheel that has traction.

 

+1