I often hear people asking if a particular vehicle has an auxillary gear system. Please I would love to know the benefits of this in vehicles, constructive comments are highly appreciated.

If the 'auxiliary gears' is in offroad vehicles and some SUVs, then you're referring to locking differentials. They are used to 'shift' power from the engine to either the rear wheel or front wheel or all wheels so as to lock the wheels together and gain transmitted power, torque and traction thus enabling them to move over various types of surface (rocks, hills, sand, mud, gravel, grass, water logged areas etc).

Thanks