People who are saying about children doing the same ITS BECAUSE THEY ARE CHILDREN, once you get above the age of 18 you should have a little common sense and respect for someone else's property and there is no excuse not to.
Some of the gf's on here would be gone double quick if they did these things and then came out with the crap you are quoting.
I can't stand idiotic people who are incapable of taking something on board and try to justify they idiocy with statements like "its only a car".
If they can't respect something that you like, whatever it may be, then ditch them. It seems to becoming more and more common for people to be so arrogant and stupid that they can't apologise when they have done something wrong.
Does it not strike you that some people never learn things because everyone makes allowances for their issues. If she can't understand that you like to keep your car in as good condition as possible for whatever reason, then she can walk.