I have a 2008 Toyota Prius Package #3. Mine didn't come with the factory navigation since it's a package 3 BUT it does have the MAP button on the steering wheel. When you press the button it says "The external system is not connected" on the main display. Now I've read that it's not possible to install the factory navigation on a Prius that didn't come with it but I am finding this very hard to believe as no one seems to have any substantial evidence. Not to mention when you press the MAP button on my wheel it obviously works since it says "The external system is not connected" on the main display. That means that obviously the map button works but the system is not there and not plugged in. Does anyone know if it is possible to buy the external system and make it work because so far the answers I have seen of people saying "no" have no evidence or facts to back their answers up.