Heh, no idea. From what I gather, it wasn't "hey, let's race", but more like speeding silently next to you, daring you.

I remember some (non-police) guy did that to us before. Dad raced along with him until we met another car in front doing normal speed. We lined up next to that one and slowed down to match it, barricading the racer guy on the 2-lane street. (there was a concrete wall between us and the opposite lanes).

The guy was pissed and started tailing really really close. We tapped the breaks lightly and scared them shitless :P