Does anyone know if a 2008 radio will fit in an earlier car? If so I think you would be able to buy the sat module and antennea - but then would the navigation drive still work?

Im not sure what year they switched to a DVD based nav unit,,

 

Ask the dealer... and even they might not fully know so you might want to ask the factory directly. It also comes down to a programming to the car's hardware and wiring loom issue plus if the connectors are all the same. Not as easy as it seems with these systems. i do know you can not retrofit Bentley's high-end audio Naim system in a normal Bose audio equipped car.