4WD necessary?

SUBARU Active Torque Split Automatic Trans-Axle is capable to cut off the clutch to transmit the torque to propeller shaft by shortening the electric actuator circuitry, so even possible while running. In short we can on and off the rear traction while driving.

Realized I this function could prove the error of thrust between frontal vector and rear one. Drifting traction applied on residual wheel unnecessarily do harm on the stability of the vehicle itself.

However precisely the thrust angle has been adjusted, the electric F/R switching shows the stability change, because the thrust angle cannot be adjusted to zero degree including motor torque reaction to the automobile's body leading to change of toe and camber values.

Now I conclude the 2 wheel drive is easier to adjust an automobile go straight comparing with 4 wheel drive constructive axle design.

In another words it's impossible to establish the fine wheel adjustment and axle geometric constructive setting on 4 wheel drive vehicle, because the traction rate changes every time the outer stimulation would applied on the wheel. No one knows the direction for every wheel to go, scattered directions?

Frontal 2 wheel traction is the advantage to establish the stability while straight running. Rear drive construction is inferior to F/F designing and the 4 wheel drive is the worst if compared only on the straight forward stability.

The deeper consideration on drive trains leads us to the conclusion that 4 wheel driving axle design is not always necessary for ordinal passenger's if the climate is moderate and the circumstantial condition were normal ones.

Because additional another driving system designing invites the physical increase of body weight about 100kg, transmitting coupler clutch, propeller shaft, differential gear box and drive shaft with DIJ and DOJ on both sides.

This heavy weight increase causes inevitable disadvantages in every movement following the principle of the Law of inertia. No advantage exists except the misunderstanding of dull movement instead of comfort ride.

There apparently exists disadvantage on fuel consumption because of friction losses in unnecessary additional drive train. The engineer who must sell the specific automobile with these kind of disadvantages must has been suffered from unmovable Physical Properties?

Putting an emphasis on upper descriptions, again I conclude that no 4 wheel driving axle designing is necessary for passenger's automobile so far as it goes on a paved road in normal climate condition.