Does Google Maps for iOS work without data access or with low intermittent data access I am going on a road trip and want to use Google Maps for iOS.

The problem is there will not always be data access along the way.

Will it still work i.e. is the route downloaded when you click start or what should I do?
There is a nice feature on the Google Map app : you can cache the map. 

Just zoom on the zone you want to cache, then type Ok maps in the search bar and this part of the map will be cached on the phone !