Why not? Because she is 12? If so, then it is the owner who should somehow be arrested for stealing the car. If the girl didn't steal the car, then she shouldn't be charged with stealing it.
also, almost running someone down sounds like attempted murder to me.
She's 12. I doubt she has/had any ability to understand that what she was doing was life threatening. Therfore, it would be manslaughter at worst.
It's always been my understanding that if you are driving another person's car without their permission that's stealing. Isn't it?