I'm thinking of pouring cooking oil in someone's gas tank at the fair this weekend
What did this person do to you?
She will probably try to fuck my boyfriend, and she doesn't like me.
You shouldn't vandalize people's property for any reason, and especially not just because you're assuming something is going to happen.  You don't know what this person's plans are, and even so, destroying her car wouldn't fix anything.
My boyfriend will never cheat on me, she pisses me off.
It takes two to cheat, and it sounds like you have faith in your boyfriend not to succumb to this other woman, so I don't think you need to take any action.  This woman is wrong to try to seduce your boyfriend, but it would be worse for you to commit illegal acts in return.