Its tough to control steering when four wheel are connected in front of the car in our indian roads. Also if there is more wheels, the power transmitted from engine to wheel is more. we need advanced suspension, and braking system. In case of six wheels, its better to place two wheels in front and four wheels in rear and it should be rear wheel is to get powered. so that front wheels are controlled flexibily.Selection of tyres to give equal performance to the output of engine.we have to maintaing exact camber angle in order to get perfect handling.