Not all Vette owners wave, only those who really appreciate the car. Vette owners who purchase Vettes just to drive a Vette don't seem to wave back. Those who drive a Vette, who believe they are part of a tradition, wave. I wave to other Vette owners, and you would be surprised how many do not wave back.
Wrangler owners wave to other Wrangler owners, but not as frequent as Vette owners.
Problem I see with Hummer owners is that there are too many soccer moms and dads who drive H2s, and they might get the idea that you are flipping them off (especially in MI).
I doubt if I will be waving to any Hummer owners, unless they wave first, at which time if I have time to react, I might wave back, but I will not initiate any waves unless I know the person.
One of the notable things I noticed when moving from TN to MI. In TN everyone waves to everyone with a FULL hand, here in MI, most waves only utilize ONE finger. (Yes I hate MI.)
