Jada barks in the car too..especially when we pick up my granddaughter at school on Wednesdays..she barks at every kid that walks by the car and she loves kids.
Jada was over 3 years old when we adopted her, so we don't think she was ever socialized as a pup. She is good in stores and if I take her into work...she only has this attitude in the car and at home.