The Sygic app on Android/iPhone uses only the GPS radios in the cell phone to locate you. 3G is not required for location. You can use the maps in airplane mode (with only location service enabled). The maps are pre-downloaded, so need no data connection. Its extremely reliable, and pinpoints location within seconds (no data connection required) You can select which country maps to download. Do this over a Wifi connection to avoid data charges. Once you download, you can navigate easily, without a data connection. (I am currently in Poland so its showing these street names) There are a few other nice features: HUD gives a 'heads up display'. Works well at night - place your phone on the dashboard and the map gets reflected on the windsreen The best part is the 'Travel book' All your maps are stored, along with some pretty good statistics!