Awesome! No new Garmin for me then!GPS is GPS. I've had it work fine where I have no cell signal at all.
I was on the phone for over 30 minutes, and the app never lost track of where I was, or what route I should take.
It really just depends on the specific nav app. It's certainly possible to have a nav app that stores maps locally but pulls traffic data.for most gps applications you will need a cellphone signal or wifi. Most gps apps do not down-load the maps and instead they just kind of stream them as you are going and keep you updated on current road situations.
there are 3rd party gps apps that will download the maps prior to using it but it will not be able to update if there is a traffic jam, construction etc. if you do not have a way to connect to the internet.