I have this in my car: 
https://www.amazon.com/Kenu-Airframe...u+phone+holder
It works great! The vent slots in my car are horizontal.
We have this in my wife’s car: 
https://www.amazon.com/iOttie-Holder...t+phone+holder
However, the vent slots are vertical in her Toyota and the weight of the phone sometimes causes it to flop from side-to-side
We also have  this for the iPad: 
https://www.amazon.com/iKross-Smartp...p+holder+mount
This is great for road trips where I want to see a larger map.