For anyone considering using their UMPC as an in-car GPS device, you'll want to be watching GottaBeMobile's latest InkShow video. In it they take the ASUS R2H out and put its in-built sat-nav receiver to the test, using Microsoft's MapPoint 2006 to plan a route and test out the audio directions.
At $998 retail it would be difficult to justify the R2H simply for its abilities in guiding you, but as part of the unit's overall capabilities it's another string to this accomplished UMPC's bow. If you plan to use it or another UMPC in the car then you might be interested in The Carrypad UMPC Journal's information on different mounting solutions, too.
ASUS R2H GPS InkShow [GottaBeMobile]