Alfa Romeo Mito Phone Adapter v4
Remix removes all the voids and strengthens the base.
The ball mount is now 17mm, which fits e.g. Baseus Metal Age Gravity Car Mount (CD Version), possibly many more.
Use 100% infill and/or 10 wall loops, this needs all the strength it can get. Don't use basic PLA, it will melt in the car. I've printed mine using Sunlu PETG-CF on Kobra S1 with a hardened steel nozzle, but it's probably overkill, just use PETG, ASA or ABS.