The knob selects 2WD, Automatic and Lock, with the latter locking the center differential. Down on the console, a separate gear shift lever selects 4Lo. It seems to me both operations could have been consolidated into one rotary switch operation as Ford and Chevy use on most of their 4WD sport utes. Or Infiniti could use a multiple position floor shifter - similar to the one in the Jeep Grand Cherokee. Given a choice, I'd prefer the rotary switch.
Cargo space is on par with other SUVs that stow the spare under the chassis.
To fold the rear seats flat, the rear seat bottoms must be tilted forward, afterwhich the seat backs can then be folded, but only after removing the headrests. This is somewhat of a pain in that you now have to find a place to stow the headrests. That aside, cargo loading height is a comfortable 30 inches to the sill top. Although the QX4 comes with nifty running boards, I found they're really not needed as the step-up into the cabin is a low 18 inches. It's probably one of the lowest of all SUVs in this class.