Our friend drove one of our cars and crashed into another one of our cars. Is the drivers insurance responsible for damages?

Depending upon the state you live in, the answer may vary.  Typically, the insurance follows the vehicle, not the driver, so the father’s insurance should cover any damage and bodily injury caused by the accident.  But if the father did not give permission for his son to use his truck, generally he will not be held responsible.   If your son’s friend does not have insurance but used the truck with his father’s permission, his father could also be held liable.  If the damage exceeds the value of his insurance, the father’s personal assets could also be at risk.  To sort out this situation, I would advise speaking with an attorney who specializes in auto accident claims.