The torsion bar rear suspension on the GSW is not a simple torsion bar setup like I had on my 80's vintage FWD Audi Fox and Audi 80. The two rear wheels have swing arms and the torsion bar is about half way between the swing arm pivot and the rear wheels. This configuration causes the torsion bar, which is quite large, to act as an anti roll bar. It also decreases the apparent unspring weight seen by the wheels.
Pros: acts as anti roll bar
Vehicle:
Volkswagen