Did notice that on that self parking car clip that the car did'nt have to pick up a car park ticket or pay at a barrier.
And if the car gets bored in the car park does it go off for a drive on its own?
On a more serious note though I would not let the car go off on its own and out of sight. What if the system fails, how would you find your car if you did'nt know where it parked itself?