Remember this story? During the Ferguson riots, a pack of teens surrounded this Bosnian man’s car. He got out to confront them, and they killed him.
http://www.foxnews.com/us/2014/12/02/protests-sparse-after-pack-hammer-wielding-teens-beats-man-to-death-in-shadow.html
He shouldn't have gotten out. The car is your protection and weapon. Your only real concern is using it lawfully, and for that you have to be able to show that you were legitimately afraid for your welfare or life. That's why you let them break something before you floor it. And laying on the horn is clear notice you're not cool with what they're doing - as if that even has to be proven, which it does these days.