Property is property, it hardly matters just how one aquires it(most of the time) , if it's legal. She could have been borrowing her dad's car for the night. Even if it is her car, from daddy with a big bow on top, that hardly makes a group of supposed 'men', destroying it, any more justifiable.
Regardless, her property is no more morally valuable the beater down the street that also got torched. What is admirable, albeit foolish, is the extent she goes to trying to protect it. She is a tiny girl, throwing swings at an angry mob of drunken, worthless, morons.