[jonursenbach]

If you're using Google Maps every day, you offline your area within the app. Drastically reduces data usage.

[votepaunchy]

Shouldn't Google Maps be caching this data?

[dharmab]

Offline maps allows you to save all of the streets in a large radius, the size of a medium-size city. You can also save an area in advance, such as if you're going to an area on a trip.

Caching just saves the streets you get routed on, after the face.