回複：4X4 is more simple than AWD, right?

Put this way, if all 4 wheels touch the road at all times, I would say either you turn or go up/down the slop you won't see any difference. But if you are driving with one wheel off-road or the worse case two wheels off-road, AWD is your choice. It won't waste any power and will manage to get you out of the rough/bumpy/slippery road.Here slippery road will make you lose one or two wheels since they won't help you anything. As AWD system senses that it will redirect the power to the wheels which will contribute to drive the car out of the situation. Hope this answer your questions.