The Lunar Surface Edit
Duke Nukem uses the Rover to drive along the moon in order to get to the Alien Empress, The Rover has the speed and strength of the now-destroyed Mighty Foot which allows it to jump massive ditches and knock down any alien dumb enough to get in its way. The Rover also has a power cell which needs to be replaced by Duke half-way through the trip.
Fighting the Empress Edit
The Rover is the key tool to use when fighting the Empress as it is needed in order to ram through the weak points in her legs, weakening her and then ramming the Rover into her chest in order to allow Duke destroy her organs. After her internal organs are destroyed by Duke, he rams the Rover straight down her throat completely ripping her internal organs apart.