If your father allowed the girl to drive, then if the girl was at fault (e.g. driving negligently or carelessly) in causing the accident, your father would be liable, too: the owner of a vehicle is liable for the actions of those he permits to drive his car.If she did not have permission to drive, your father should  not be liable--but not having permission to drive means she stole it, which means your father would need to press charges against her for theft and credibly show that she did steal it.