How do I use UserInputService to turn a players cars lights on?

I have a grouped car model, however if multiple people are in the same game with the same car there will be multiple of these models in the Workspace with the same name. How would I get the exact car that the specific player wants to turn only their cars lights on with UserInputService in a Local Script? Where would I put this script and how would I tell it to find the VehicleSeat with the local player in it?