When I had my STi, everybody with a Subaru waved at each other. I got people in Forresters, WRX's, Legacy's either waving, throwing the peace sign, or flashing their lights at me when I first got the car. I thought it was weird at first waving at other Subie owners, but then after a while it was second nature. I just waved back, flick my high beams ect. It was pretty cool.
When I got my 335i, I tried waving at a couple other Bimmer owners, another 335i and an M3, they both kinda just stared and then dogged me out.
I haven't seen many other 370Z owners around here, only 2 but they were parked, but I have had a couple 350Z owners rev at me and try to instigate a street race.
It seems the 350Z owners are very aggressive, they seem kinda pissy all the time, on the forums and out in real life.