[Razel]

I have a K1300GT BMW motorcycle that I got with a BMW Navigator IV. It's a Garmin Zumo 660 rebranded by BMW. Works great on the bike, and with the bean-bag mount in the car, gives you the chance to use both in the X3. The 660 is far easier to use, but I've had over a year of practicing with it. What's really nice is that the 660 stops trying to get you to your destination after you've reached it, without having to turn off the ignition.
You also get the current speed limit for the road your driving on, your speed (yup, the X3's a bit optimistic, but that's good), elevation, and some other route/trip info that's not available with the built-in one.

But, for the most part, the built-in one handles 90% of what I need, so it's usually solo when I'm driving.