We are exploring the option of getting the car dock for my Atrix 4G and retire our old Magellan from early 2000's. How much data does the navigation app on the 4G use under "normal" point to point directions usage? (on OS 2.3.4) Have the corp 2GB plan and don't generally use much data off wifi, have wifi at home and work. So if I use the nav program with GPS for say 3-5 hours a week-2 weeks will I burn through my data plan?