I read a lot about this but I can't find a satisfying solution.
I want the Pi to automatically power on when I start the engine and to cleanly power off when I turn it off.
what I thought was to power the Pi from the vehicle battery using a 12v to 5v charger and to connect it to the cigarette lighter socket through a 12V DC DPDT relay, which shorts a pin configured for
dtoverlay=gpio-shutdown when I turn the ignition off and shorts the RUN pin to resuscitate the Pi when I turn the it on. see image below:
the problem is that the Pi doesn't boot when I short the RUN pin but only when I reopen the circuit between the 2 pins.