My station is set to auto track.
I have it set to center on map.
The map is zoomed out the size of the county (about 100 miles, maybe less).
I can travel 5 miles or 20 miles, and the map will stay at the zoom level I left it.
Randomly it will fully zoom in when traveling or stopped (usually does it when stopped for some time).
I will then zoom back out to where it was, and it will typically - but not always - fully zoom back in.
The this occurs, the station never leaves the map area and is still generally within the center of the map.
If I travel outside of the map area, the same zoom level stays (usually). Then it will zoom all the way in when it wants to until I again zoom all the way out.