Are you Planning to Support Offline Maps/Routing - how can I Reduce the Data Usage

Yes, this is definitely on our road map. Give it some time :).

The Kurviger app has a very low network usage. If you want to reduce your mobile data usage, disable hillshading. Once the app has seen a part of the map, it is usually available offline, so when you are planning the route, you are already downloading parts of the map, that are reused during navigation.

If you happen to be offline or cannot go online, this might be possible. You have to have internet to plan the route, once the route is planned you can navigate along the route offline. When you looked at the map before parts of the map might be available offline as well (see above). Otherwise you have to follow the route using the navigation instructions (they are available offline). You will see your location, the route itself, but no map.