I'm not 100% sure I understand exactly your needs, but I doubt there is an all-in-one PND (personal navigation device) on the market today which would output signal which your CarPC could use to display the moving map. Perhaps, if you have enough money allocated to this hobby, you could consider buying one of the very small UMPCs (Ultra-Mobile PC), such as the OQO 2 or Sony UX. These are Windows XP / Vista computers. They are so small they fit into your pocket. Screen size about 5", just like the all-in-ones. You could install some
PC GPS navigation software on the tiny computer, and use it anywhere. These devices output VGA, so you could use the monitor of your CarPC to simultaneously display the moving map, or you could try to integrate it with your system in a different way (don't ask me how - I don't know
).