Ron,
I tend to check out any of this stuff on snopes.com...
http://www.snopes.com/crime/warnings/carjack.asp
In the personal security classes I teach, I go over situational awareness in parking lots and other public places.
It's best to be on "yellow" level alert at all times. That means you're aware of your surroundings; who is present and take action when you feel uncomfortable for any reason. "green" level would mean you're oblivious to your surroundings - which is how many people go about the world...
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Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.