There was no tone when I opened the door, not that I heard anyway (it was a 2017 Citroen C4). The dashboard may have stayed lit but as it was a hire car I had no idea what the normal behaviour should have been. I had two passengers who also did not notice anything out of the ordinary when we left the car. A colleague had the same thing happen in a C4 but he was still in the car when the engine restarted.