Hit a nerve, here.
For those who didn't follow the thread far enough, Dr X has some intersting actual research that has been done on road rage and bumperstickers, plus his (her?) expanding on the topic. It is especially gratifying to me, as I often agree with Dr. X, but have sharply disagreed with him on our last two online encounters - I may even have said "balderdash," which is quite stern - and am pleased to illustrate my general goodwill.
Also, I tread on dangerous ground. My wife puts bumperstickers on her car more than I do on mine. Certainly, if you asked 100 of our friends which of us was the more narcisissistic and aggressive, less than five would choose here. And the only reason it's not zero is because we have a few contrarian friends who would go out of their way to find evidence why the obvious answer isn't the right one.
And yet, maybe it does hold. Tracy's bumperstickers are usually about libraries or reading, and on that topic, she may indeed be narcissistic and aggressive. She actually tries to put those stickers on the cars of other family members. So if we restrict this to specific aggression rather than generalised aggression, the point still holds.
And she is a more aggressive driver. Scares the pants off me sometimes.