The navigation computer in the trunk of the Rover is the "brains" of the navigation system. Think of it as simple as the monitor is just a computer monitor and the nav computer a desktop computer. It is the hardware and software on the navigation computer that displays the information on the display. Otherwise the display would be useless. The BMW MKIV DVD navigation computer is MUCH faster and supports 3D map viewing, plus the software supports more additional upgrades such as displaying song title and artist names on the display when playing MP3s or Sirius Satellite radio.
The MKIV navigation computer supports 3D map viewing in much better graphics.
Using the MKIV navigation computer your map position is easier to determine as the map data passes under the vehicle mark.
Information on the BMW MKIV Navigation system (for use in the Range Rover)
MKIV DVD based Navigation Users Guide
Functional Overview of MKIV navigation computer with details and photos
Open the Storage compartment on the rear left side of the car where the navigation computer is located
Insert a "radio removal tool" into the 4 holes on the navigation computer. Slide Range Rover navigation computer out, replace with BMW MKIV DVD navigation computer. If you do not have a radio removal tool, cut a coathanger into 4 pieces and insert the 4 pieces into the holes on the front of the naviation drive.then pull straight outward. DO NOT disconnect the power wires from the Range Rover navigation drive until the light on the navigation drive goes out!