I understand your dilemna, since owning ours i've had to bollock one near neighbour for her shoddy parking - she left her car front bumper to front bumper with ours, luckily no damage but i didn't half let her have both barrels (no swearing mind otherwise you've lost the high ground).
I've also told the kids off for skateboarding around it - they ollie up onto the pavement next to it and that's a big no-no. The umpteenth time of doing it i sternly spoke to one of them, felt a bit bad so gave it 10 minutes and then went over to calmly talk him through why i didn't want him pulling tricks on his skateboard next to his car. I was once young, however my dad would have bollocked me rather than a neighbour for doing something like that around other folks' properties but what can i say, standards are obviously slipping, parents don't care etc...