When in the box, I usually wave to any other Porsche I see. Rarely do I get a return wave up here in Chicago, but that doesn't bother me one bit...
Now the motorcycle is a different story. I always give the "left hand down" wave to other bikes, and almost always get the same in return. Even though I ride a Harley I wave at all makes and models. A lot of the "die hard" Harley guys will only wave to other Harleys, but since I spent 10 years driving crotch rockets before I became a "Harley Guy" I will acknowledge any bike, regardless of make or model.
Now if it would just warm up so I could drive either one of them I would be a happy man
Nick