This car automatically stops (or tries to stop) when you let go of the Pitch (=engine input). Works in both direction.

Back from a little hiatus!... or not.
Sorry to those whom I haven't responded to. I'll (hopefully) start responding to comments bit by bit (if I remember about it. Notification field doesn't help).

This is a demonstrator for a rudimentary auto-braking FT. It uses WheelRPM & FT input for the engine to try to stop the car when there's no manual engine input. It simply runs the engine in the opposite direction of the wheels until the wheel speed is 0. You can probably improve the FT.
Obviously, the orange stuff are the ones you wanna dissect.

I'm fairly sure you can use something like this to make a vehicle completely stop on a slope, but I'm neither smart enough nor dedicated enough to try.