shy and scared dog

Question
I have a two year old whippet mix, that I have owned since she was a puppy. I got her from a rescue and she is very scared of people and car rides. She never has acted aggressive, and she even sometimes will wag her tail a little or act like she wants to see a person but is too scared. I have also noticed that the younger the person is the better she will go to them. I have been teaching her what I know of obedience at home since I got her, and at home she does very well now and has learned a lot. But after we go on a car ride or she is introduced to people she acts like she's some kind of doghouse dog and just wants to bolt. I just want some suggestions for how to get her to calm down, listen to me, and to the obedience tricks she knows very well now when we go somewhere or meet new people.

Answer
Well what you can do,is have people that she will come to give her little treats as they pet her,so she knows it's good to let people pet her

And for people that she won't come to,you can pretty much try the same thing,again so she knows people are good

It is a good idea to work on training,as that often builds confidence-so it won't hurt to get her enrolled into obedience classes