Interesting. Never heard of this on a factory radio.

The empeg itself does not have this, it clearly indicates the range of the volume control. As you've already seen, right? It shows the top of the voume scale clearly on the screen, so when you reach it you reach it. But at least it tells you clearly where minimum and maximum are, it doesn't lie about where the top of the scale is.

If you use an FM modulator to send its signal into the factory radio, then you are at the factory radio's mercy as to the volume level. So I guess the answer is, yes, it would still do this as long as the factory radio still did it.