Traveling whit Treo

In winter vacations, I travel whit my family by some states in Mexico. We arrive first on Leon, Guanajuato, and then my father has the ocurrence to go to Zihuatanejo bay.... the first time we do that... so well I got my Treo, open Googlemaps, ubicate our position and begin to follow him.
Obviously, the Treo and the excellent Google program dont let me know where im goping like a GPS, but i follow the road and I can probe that Mexco in some states has great coberture cause between Guanajuato and Morelia I never loose the connection. Just till Guerrero state I lost signal but its good to know all country even in roads we have a good comunication.