My ds2 and his friends found a very recently killed cat at the side of the road yesterday. They contacted the owner and waited until she came to collect it. She was obviously very upset.
One of our cats was also killed on the road a few weeks ago. A pedestrian found him and took him to a vet, who contacted us (he was microchipped) but unfortunately he'd died by the time we got to him.
In neither case did the motorist involved stop and attempt to contact the owner of the cat they'd killed. I understand that cats running out into the road isn't necessarily the driver's fault, but if you've killed an animal, even if you don't think it's your fault, shouldn't you stop?