I usually raise my hand slightly off the handle bar when I'm riding my motorcycle, both hands have to stay on the bar here in MI with all the damn pot holes and people using their cell phones or doing something else beside paying attention to their driving... Anyway, I don't know if you can call it a wave, its more like a polite recognition of a fellow rider regardless of the type of bike he or she is riding (More like a brotherhood).
Now when it comes to the XF, I only wave if I'm being waved at, unless of course its a she XF driver...