"Onze auto is gestopt."
Translation:Our car has stopped.
You can stop doing something or stop someone from doing something (so, hebben gestopt) or you can be going somewhere (motion involved) and then stop (so, zijn gestopt).
Ik heb hem gestopt.> I've stopped him.
Ik was aan het rennen en dan ben ik gestopt. > I was running and then I stopped.
You translate it most of the time same, then the context will tell you in which tense it is,''Onze auto is gestopt door de politie.'' (Our car has been stopped by the police.) But another option is to say ''Onze auto is tot stilstand gebracht.'' Which means that the car is brought to a stop (hopefully that is good English :)), but that sounds a bit too polite to my Dutch ears.