Show in-app status and send push-notifications on open windows, doors and locks
My personal experience with the Volvo XC90 is, that it sends the users a notification through the app that they've left a window open or door not completely closed, after locking the car. Can't say a lot more about it: it's just GREAT. It saved me once when leaving the car on a sunny day at an unattended parking lot with an open window.
Moreover, having that status shown in the app is really comforting.