@Stefan-Hummelink, I think the max. zoom level is not upped using this feature, like I explained here:
https://forum.myrouteapp.com/post/33107
If that is true, setting ++ will effectively disable auto-zoom and always show the maximum zoomlevel.
I agree that a more distinct difference in zoomlevels is welcome. Meaning, a bigger zoom out on highways at high speed and a bigger zoom in on crossings and slow speed.