This is for older car models that do not have built-in navigation or bad navigation. My car is old enough to have a cassette player.
This model is made for a Toyota Yaris from 2001 and the phone inside is an S21 Ultra that would otherwise have been sitting in a drawer.
I have sacrificed the original sunvisor to get the swivel part out and modeled a new sunvisor around it. Since this car is really old it's okay to make these modifications.
So far the driving experience has improved a lot, it is a pretty decent location for a navigation system since you can focus on driving much more easily than having to look down and to the right.
The models and FreeCAD design file may be found here:
https://www.printables.com/model/1256013-toyota-yaris-sun-visor-with-navigation-phone
How does it handle the heat of being in a car? The mirror housings I made for my dirt bike got a bit soft just being outside in summer sun (until I annealed them), and inside a car can get pretty toasty. My mirrors were PLA though, if you're printing with higher temperature material it might not be an issue.
I've also printed a few thingies for the car and my experience is, PLA deforms on the first hot day and you can throw it out. PETG lasted 2-3 years for me until it became brittle and broke.