guys, you do not need an Internet connection while driving. all you have to do is: while you are at home or at a place where you have an Internet connection view the area you are going to be driving in, say Dallas for instance, zoom in and scroll around. google will cache in the map data on your hard drive and make it available to you if no Internet connection is available.
Where the problem shows up is if I wanted to take a trip, say to Houston, and I have not browsed the maps to Houston on in Houston I would then need GPRS or EDGE or some means of Internet.
Like rebelleader said about the bandwidth, I dont think GPRS will cut it. I will try to test it this afternoon.