The amount of cellular data that the My ONE20 app uses can vary greatly depending on how you use the app.
If you choose to download and use offline maps, the app can function on a very small amount of data. When offline maps are downloaded and used, the app will only require data when navigating if you enable the ActiveTraffic setting. When this setting is used, it will need data to update live every five minutes. Additionally, data would be needed to use the Plan screen and to access deals.
If you do not choose to download and use offline maps, the amount of data that the My ONE20 app needs to function increases. In this case, the navigation, trip planning, deals, and other sections in the app will need cellular data to function.