We had a similar problem in our block last year when a car was left in the car wash for 3 months.
This car had been a regular “visitor” for some time previous, so it was known to be associated with a resident of the building, but there was no way of telling who. Notices on the car and around the parking area failed to get a response.
It eventually transpired that the owner was in the Defence Force and had been posted overseas. He asked a friend (non resident) to park the car in the building, and the wash bay was the most convenient spot.
Our OC is self managed, with one person owning about 75% of the lots, who is quite happy to allow his tenants to use the visitors spaces for overflow parking.