@Dikke-Wim, this is a comment that gets made every now and then, mostly by newcomers (no offence) that have missed the reasoning behind it. The navigation app makes deeply use of functions and features that are delivered by HERE and their software development kit. It is not intermixable with maps from other sources. The choice of maps in the planner is largely meant to make possible to compare between different map sources, and make them equal. Developing a navigation app that makes use of OpenStreet maps or TomTom maps would account for a completely separate app, based on other SDK's.