Can you show more than one car on your Tesla Phone App?
Yes, I have an X and 3 and you can switch between them. Just note that if you have the app on the X and want to open or drive the 3, you must switch to the 3 on the app or the phone is not recognized by the 3. Not a big deal and you get used to it.
You just swipe left and right between cars.
I've an S and an X on the same app and have no problems. Seems to have full functionality regardless of which car I'm looking at.
The 3 unlocks with the phone so if the app is not on the 3, it won't unlock.