We are travelling for holidays for some time and since I am already getting a new car, I decided to remove the control plates from the old one, annul the grey card (fahrerausweis), and let it stay in another parking spot (indoor) until a buyer is found. Verwaltung has already been nice to point me to a temporarily empty spot.
Now, is there anything else I need to consider/do apart from going to Strassenverkehrsamt, putting the plates in their box, and having the grey card stamped as "annulled"? Any special consideration?
And what are the rules regarding cars without license plates? I assume I will not touch it at all, but is it okay for example to move it inside the parking lot? Or I must not switch it on at all?