When I was a kid, I remember hanging out at night with my buddies and we made a game of guessing what was coming up the street, before we were able to get a good look at it. I got pretty good at it, and could tell, by headlight arrangements, reflections off of bumpers, overall height, and even in the dark, what was coming up the street.
Sound had something to do with it, too. If it was four horizontal headlights and the deep burble of a 383 with duals, we needed to get back to the porch - that was the unmistakable combination of the local cops, and we were probably out past curfew.
Always wanted one of those Police Package Satellites - pretend I'm Kent McCord in Adam 12 . . .