You can move your car if you don’t feel safe, it just has to be “reasonable” or within reason.. but once the car is moved it makes it harder for the cops to properly investigate the accident.. so it’s best to not move the car. In NJ your insurance covers you regardless of whether or not the police find the other driver…. So you don’t really have to worry too much about that. The only difference it makes is if the other driver isn’t found, then they get away without getting tickets that they might deserve.. which is annoying but it’s not the end of the world for you.