The Tesla mobile app should have 2FA (two factor authentication). It's entirely feasible to steal a Tesla by compromising an owner's account.
Tesla Mobile Key is the same as car keys, so having the option for the car to make a noise when the phone key is left in the car is a necessary safety feature.
Currently the Model X and Model S does not support using your phone as a key (as passive entry). Sometimes it's nice to not have to carry around a key fob.
The idea would be to bring this same feature that's in the Model 3 to the Model S/X.
It would be convenient to be able to customize the walk-away door lock settings (by geolocation), for instance to disable it when you're at home: in reason of the key fob's signal range, my car keeps opening and closing randomly in my garage when the key fob is anywhere in the ground floor.
Be able to directly link to car via app or key or Bluetooth in UK to enable summon without mobile signal dependency.