[BR3W CITY]

Old car drivers up here acknowledge each other for the most part, and then generally extends to hot-rodded late model cars and truck for some folks. Its not always really a wave ;

The full wave is older generations mostyle, but its "polite". You'll see a few raised fingers from the wheel or the window for the subtle notice. IMO Putting the deuces up is a little more gracious or more directly acknowledgement. Its also not uncommon for some to do a small salute, light honk or of course the classic thumbs up. Even the "metal" horns from time to time.

I do see some cliques or subcultures gravitate to one or the other.