AutoInput HTC Car Mode

Hi Guys,

Im a total newbie (and Im age 47 so give me a break! haha)

I have a HTC Desire 626 NON ROOTED permanently installed in my car connected to my cars head unit via USB/mirrorlink. I use Tasker to start 4G, Bluetooth and HTC Car App when it has power. Tasker also switches off 4G and bluetooth when power is off. However HTC Car App continues to run which in turn keeps the phones screen on. If i forget to manually close HTC Car App or forget to switch the screen off at the phone the battery runs out in about 8 hours. To manually close HTC Car App you need to push the phones back button (this makes a small pop up with "Are you sure you want to close CANCEL OK"

Guys, how do i use AutoInput to automatically close the HTC Car App? I have no idea :-(