most portables still need to be updated via expensive DVD's and computer connections. you will get a much more usable screen, less clutter, less hassle, and better integrated operation with a built-in. but you will save vast amounts of money by going portable. in my case, i got a REAL portable, that I can hike with, mountain bike with, drop-kick, submerge, etc. It also does auto-nav, but with memory limited to one large metro area (NorCal, for instance). Those functions were more appealing to me than the auto-nav advantages of the built-ins, and for far less money. So I didn't bother trying to find a car with Nav built-in.