Because i live in Porsche country near Zuffenhausen there are too much Porsches around. So if i'm driving in this area i only wave to 986 drivers. Mostely they wave back. But some don't.
If you wave to 996 drivers, sometimes they wave back. 997/991 drivers seems to have no hands to wave back.

I also know that i only drive a 986 - so i'm not smart and rich enough to get their respect.
924, 944, and 928 drivers mostely wave back.
Never tried to wave to Panameras, Cayennes, or Macans. Have no experience with 911 G, or 993 drivers.
Regards