You don't have the conversation with the car. You do what the OP was eventually urged to do by people here who are more mature. You make the phone call to report what happened in a rational way. And then you let things take their course, which is what happened.
I'm sorry, but I can't imagine that the cop nearly brushed a kid in the street with her car. " Stop walking" would be the logical thing to do even if the car is 4 or 5 ft away.
While I am not trying to paint all kids with the same brush, I have to say that after having worked with teens for several years, and seen how they react to things, I would almost guess that the OP was with friends leaving school for a half day off and happy about getting out early and when the car came close (which I admit that it might have done) the OP had to show off by yelling. I've seen it over and over, that teen "quien es mas macho" comes to the front very often. Kids need to learn that yelling out is not always appropriate.
Finally, who is it that is supposed to teach young people respect and courtesy so that they can get along in the real world without conflict? What are they going to do when their employer wants them to do something that they don't like to do? What if they have to deal with a customer that is demanding? What are they going to do when someone cuts them off in traffic? Who sets the example for those things? Or, do we just let them yell in the street and tell them that it's ok?!