How much data does Google Maps navigation use? Does anyone have a rough number for how much data Google Maps navigation uses per, say, 100 miles or something? I know it will vary slightly by user and area, but I'm just looking for an average/estimate. 

I'm going to be driving to Canada soon, and trying to estimate how much "International Data" I should purchase on my plan to cover the Google Maps Navigation.
Okay, I did a brief test the other day... only drove about 80 miles, ... obviously longer drives would give better averaging samples. 

But from my short drive, it seems that Maps navigation uses roughly 1 MB for every 10 miles.