If my experience is anything to go by then buy a vauxhall corsa. Got further up the farm track than my 4wd touareg at white rose wood
Its all in the tyres. even a 4x4 will struggle without a decent set of offroad boots.
I would agree a small amount with that, once a trye tread is full of mud it will not grip, it acts like a slick. that happens with AT's and MT's as well,
The main thing that stops a 4x4 is the Driver, followed by the car its self, I have driven a 4x4 off road for many years, and have found AT's, MT's have their place,but also have their limitations,
My self I have been off road using road tyres and far out performed lots that have been on All Terrain Tyres let alone Mud tyres on the same off road course on the same day at the same time.... most the time I use AT's,
The Touareg is a Cross Over, like most of them , most don't have low box.. or diff lock..., most of these Cross overs are only really designed to look like an off roader, but have all the ability of any other car, with the benefit of 4 wheel drive.... also being heavier means more to drag/pull through it through the mud.