So I've read on this forum that Quada-Drive II is the best Commando four wheel drive system. It is however, an "all wheel drive" system, right?
Just to clarify, all wheel drive systems are generally categorized as systems where all 4 wheels are engaged all the time, typically without any additional 4WD capabilities.
The closest thing a Jeep Commander has to all wheel drive would be the Quadra-Trac I 4WD system - but even Quadra-Trac I has the additional enhanced capabilities of 4 wheel traction control and electronic stability control, which in my view, makes it more capable then just a normal "all wheel drive" system.
Once you step up to Quadra-Trac II and Quadra-Drive II, you now have a 2 speed transfer case at your disposal which gives you the ability to drop down into 4-LOW and this is the distinction between an "All Wheel Drive" System and a LEGIT 4WD system in the realm of today's technology. Both Quadra-Trac II and Quadra-Drive II use the same NV245 transfer case.
Then Quadra-Drive II gives you the additional capability of an electronic limited slip differential which is as good as it gets in the Jeep Commander world.
Rear end gearing is also a factor.
4WD Commanders that are Trail-Rated will have 3.73 gears in the rear end for maximum low-end torque.
I have Quadra-Trac II with 3.73 gears and even without the electronic limited slip differential, I'm here to tell you that when I drop into 4-LOW, it feels like there isn't anywhere I can't go.
My XK is a Big Blue Tank.