I am not sure if what i stubled on the other day is common knowledge or even if I am wrong about it. I found that if I am ion wifi and i load up the navigation feature. Once it starts and i turn off the data for when i am off driving the navigation still works. I know GPS isnt suppoesed to use data unless it is tied into google maps. But iI travel to Michigan at times and I was wondering if this would help me there so that I wouldnt get nailed with any roaming charges. Now this may have been a fluke I have stumbled uupon and I may be completely wrong about the use of data and such. But I was wondering if someone could confirm this for me or tell me if I am wrong about it.
You're right the maps loads over wifi or mobile data.
Google Maps has an offline feature, activated from one of the options you get in Maps when you press the Menu button. So I believe you navigate to the map areas you want to save while you're on wifi and it saves the map for later.