Got a speeding ticket yesterday - thank you very much.

Yes, I must admit that I was going a bit (20 mph) over. What struck me as funny, though, is that I was surrounded by 3 other cars (VW Golf, Altima, and an old Mercedes) that were going the same speed. Somehow I was the "lucky" one that CHiP's finest decided to pull over.
As I started driving off, ticket in hand, it dawned on me that the similar thing happened last year on my way back from Vegas - train of cars, I was pulled over. Got me thinking about the thought process used by cops in deciding which of several speeding cars to pull over. Anyone have any ideas beyond 'he who has the most expensive car must have extra $$$ to pay for tickets', which is what I've concluded???