I'm running KitKat and can't locate the Car Home app on it. It's listed in the Play Store as "Installed" and also "incompatible with all your devices", also "not eligible".
There's a seeming incongruency in the app install versus availability, and an inability to access the the app on my devices: no icon, no ability to add a shortcut to the launcher?
I've not seen another app in the Play store reporting itself in this odd manner. My immediate assumption is it has been discontinued and/or is installed in the Android OS but only makes itself available under certain conditions (e.g. a docking station is present).
There does seem to be discussion around the Internet about the Car Home app and docking station integration.
Back in Gingerbread days I used to open the Car Home app manually to use it. I haven't checked for it in a while.
Currently I'm running a Nexus4 with KitKat but I think this doesn't seem to matter. The app also won't work with my Note 10.1 and is not available for the old Nexus S either (lost that phone though so I'm only going by what the Play store is reporting for it).
I've settled for using a third-party app for now, however if Car Home is part of Android and the Play store I would prefer to use it.