As I was listening to a car alarm go off last night (and again this morning), I wondered whether as a security measure they are effective at all. My guess was that the massive number of false positives insures that they go completely ignored when they go off. I was right. Transportation Alternatives has the numbers. Don’t go around thinking The Club is a better choice, either. Professional thieves target cars with The Club so that they can avoid walking around with a pry bar.