Most people, especially women have the tendency to get into their cars after shopping, eating, working and from anywhere... and just sit there doing their check books, taking notes, checking cellphone, making list or putting their make up, etc...
DO NOT DO THIS!!!
Bad elements will be watching you, and his is the perfect opportunity for him to get in on the passenger side, put a gun to your head, and tell you where to go. So, AS SOON AS YOU GET INTO YOUR CAR, LOCK THE DOORS and LEAVE.
But, if worst comes to worst, if someone is in the car with a gun or knife to your head, DO NOT DRIVE OFF. Instead, run the engine and speed into anything, wrecking the car. Your Air Bag will save you. If the person is in the back seat, they will get the worst of it, make sure you hit the side of the car where the bad person is, not the driver side, ok? That's suicide. Then, as soon as the car crashes, get out and RUN, RUN, RUN!!! It is better than having him find your body in a remote location.