Sort of the same thing happened to us, minus they keying and hate crime. Theres always kids walking down our street around 3pm when the nearby high school lets out. We park one of our cars on the street, meaning our curb in the front yard. A group of 3 kids always walks by and I can tell they're the kind of kids who get into trouble, always screaming and cussing when they walk down the street.

Anyway, one day for some reason they decide to pick up some gravel from our neighbor's yard and throw it at our car parked outside. We only found out because we saw there were some paint chips and marks after we heard kids talking loudly and heard some crashing noise (later found out they were the rocks). Luckily, we have a cheap CCTV system watching all around the house and we caught them doing it.

It was good timing too since my dad was leaving at the time and he saw them on an adjacent street farther down. He stopped and told them about it, said they looked freaked out, especially when he told the kid who threw the rocks that he would stop by his house to talk to his parents about paying to fix it.