true 4 wheel drive question

[rubberduck_10_4uk]

What does

factually correct but not really correct in terms of "drive"

mean?? Not sure I understand this bit

Although it IS allowing equal torque to both wheels, that torque is vastly reduced from a "gripping" tyre and is eqaul to the slip torque of the spinning tyre.

Yes, posted that 

[mook]

Let's face it, when you see aerial shots of a 4WD motor steaming through the desert, you see plumes of dust shooting off all four wheels

[Coyoteboy]

Likewise you should see 2 from a 2wd, but more often than not you dont. Although you do have SOME torque going to both wheels (equal to the torque required to overcome dynamic friction on the tyre thats slipping) you wont have enough to make the car accelerate very fast, hence the notion of 3wd (with our 4wd system having an open front diff). Transmission dynamics is a lot more complex than "its just 3wd" - it varies depending on what surfaces each of the tyres are on, what is the differential of speed between the ends etc...