by vivek yadav
There are three fibers. First let's you choose a Bluetooth device(your car) and watches for it to be turned off.
Second fiber turns on gps (requires root) and saves the location in a text file. You can use an external Tasker to trigger this.
Third fiber brings up the list of saved locations and upon choosing one, shows it on your maps app.
Here is a no root version of the same flow: http://llamalab.com/automate/community/flows/6939