The security guard did an excellent job of profiling ahead of time. A guy pacing nervously while trying to hide something in his hands by wrapping a shirt around it.

Keeping your eyes on the environment around you & looking for clues is the 1st step. Just an hour ago I was driving along at 45 mph & a mini-van whipped out in front of me & if I hadn't been looking at him as I approached I'm sure I would have hit him in the side/back. I braked really hard & hit the horn and based on this kid's (driving to school) reaction I don't think he saw me. Survival in this world is all about playing good defense. Which definitely applies to the car jacking scenario.

The best advice I've read on this thread so far is "keeping a handgun loaded & ready" - of course I'm one of those crazy uncivilized Americans who thinks we should be allowed to protect ourselves with an "evil" gun.