Just hosed down the car this morning. Turned off both engine and ignition. Left the convenience key in the front centre cup holders. No issues with locking/unlocking/chirping. I did have the plastic emergency key on me, and fortunately did not have to use it, as all the doors remained unlocked (with the convenience key inside and me on the outside washing the car)

 

Well, the Q5 will not lock if the key fob is inside the car... So you don't have to start it our anything, just set it on the seat and close the door.