it is a cool program, but I don't know how you would use it on the road
ya gotta have a pretty fast broadband type connection and a CPU with some horsepower
Might be cool to use prior to setting out.
e.g.
you could easily locate the starting point (a road or intersection) then, using a paper map as a guide, you can 'fly over' the route using Google Earth.

by the way, try doing a fly over w/Google Earth of the Grand Canyon and places like that... way cool