Why does a car even need an app? Don't they have a screen and internet connection on the car itself?
Reasons I could think of for an app: Remotely check battery charge, and that would purely be for interest rather than necessity.
I get why people might like or want remote heating/cooling as well, and I'd probably use it if I had it, but it would be an exceedingly rare occurrence (although I'm more sensitive than most as to becoming a 'soft' human being).
That you know of...
/s