I know what you mean. I'm not one for segregation, I love the entire automobile community, it's a passion that unites us all, irrespective of religion or ethnicity. However, I think some car owners are either shy or just don't care about the whole "community" thing.
I still wave at Vettes because I had four over a 17 year period & the greater percentage always waved. As with any marque, there will be a few that don't understand it or the new friendships that can be made. I usually wave/give a thumbs up to any nice car, custom, hotrod, cruiser, muscle car, etc. That means they usually took the time to build/repair or restore their ride. I go to local car shows & cruise ins & it's usually a car family affair. I'm not big into owners who belittle another makes/marques because they think their ride is superior to everyone else's. I've owned American, German, British, Japanese cars over the years & enjoyed them all.