My friend threw a plastic bottle at someone's car without *much provoking....is there likely to be damage?

Skip to the last paragraph if you dont' want to read through the details

My friend and I were talking at our bus stop after school. These guys usually drive by about 10 minutes after we get there. Whenever we've seen them, they've tried being cool, waving back at us after they passed us (and curving off their lane because of it). Today they called my friend by name, which is kind of creepy because neither of us knew them (there's a chance they go to our school, but we've never seen them around) and they also threw a plastic coke bottle at us (we weren't sure if it was at us, or if they were just throwing it on the ground, but either way it just landed in the grass without hitting either of us). Then they came back down the road for some reason. When they reached the stop sign at our bus stop, my friend took the coke bottle they had thrown and threw it at their car as they drove away. They stopped, backed up, cursed at him, then drove off. Although my friend was somewhat provoked since they were being annoying, littering, and swerving on the road, it was uncalled for to throw the bottle at their car; it was just a total lapse in judgment.

Would there be any damage to the car from a half-drank, plastic coke bottle/any legal motivation for them to come after my friend? They seem like the kind of people who would do something about it even if there is no damage....what are the chances they'd do something really dumb to "get back" at my friend?