i have used google maps navigation travel from gambang RNR to kuantan before and i don't notice the maps being loaded throughout the journey. i guess the app prefetch the map once you set the destination? bear in mind i use digi, and most of the journey only in GPRS.

anyway i'm not really answer your questions since i'm not sure how much data transferred for the journey. i guess minimal data transfer since even in GPRS connection, everything went smoothly

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Added on May 30, 2010, 1:34 pm

map is the most important than the software, i have tried sygic and i don't like it at all. i'd stick with google maps navi until papago or garmin support latest android or any software that can use established community map like maps from malfreemap etc.

If u are using the Brut mod version of Maps, then yes it caches the map tiles onto ur SD card first. So u will only have to load the map once, minimal data usage 

lol, i using papago M6 with malaysia map in android 2.1, it's happened