Vertical adjusting rear view mirror

My idea is about a vertical adjusting center rear view mirror (the one in the car).
I imagined a vertical leg that allows the mirror to slide up and down on it, giving the driver the possibility to adjust it to suit his needs.

This adjustment would come in handy when a very tall driver is using a small car (a Fiesta for example), allowing him to lower the mirror in order to see the horizon through the rear windshield.
As an example, due to the center rear brake light on my Fiesta, I can see only 50-60 meters behind my car, a thing not quite pleasant on the highway.

This adjustment would also help if the driver would lower the mirror, as he would not be required to raise his vision in order to quickly check around the car in trafic.

However, the adjustment range should be rather short, as lowering the mirror too much might imply a hazard due to obstructing a part of the forward view.