GPS tracking app for car android head unit

That's not how it works, unless they also have your phone, connected to the head unit....

 

Does your Android head unit have its own 4G cellular connection and GPS? Because that's what's needed to track its location.

 

what about putting a Tile Tracker to the car? or even better, put it on the actual head unit, in case somebody tries steal that as well???

 

There's Google's Find Your Phone, which will presumably work for other connected mobile Android devices that are not necessarily phones.
https://myaccount.google.com/intro/find-your-phone?hl=en-US

If it's not turned on, you'll only see the last reported location. But then if the car isn't started, it probably isn't driving anywhere, unless it's been towed or on a trailer. There are purpose made tracking devices on the market, that will work as long as the vehicle battery is connected.