At least in the USA if someone waves you and you get hit, its their fault. Possibly why the black car took off. Still sucks either way, glad you are ok
It wasn't the driver of the black car's fault though. It was the person in front of them who caused it.
Odds are that since there's no damage to the car and not enough details, nothing will come up unfortunately. A letter to the school's newspaper won't do anything because anyone with so few morals that they'd hit someone then run away clearly won't be that bothered by a seeing the story in the paper.