I believe that Ron is right.  The camraderie of VW drivers from the early
days in the '50s is legendary.  That feeling of kinship extended to van
drivers as well.  I believe it had something to do with having an
appreciation for the unique features of the vehicle and loving it in spite of
its "ugliness", its lack of heat, its clackkity engine, etc.  If you'll
notice, the waving stopped when the VW cars(Vanagons and Rabbits) began to
look like all the other cars and had the same features (like heat).  Drivers
of the newer vehicles had nothing unique that they shared with other drivers
of VWs.  Too bad.  Since my affection for VWs goes way back, I am a waver.  I
wave to splits, bubble windows, and Vanagons.  Most Vanagon owners appear to
have their noses in the air and don't even acknowledge the wave.  Bubble
window owners look, but waving back is erratic, like maybe they recognize the
connection, but are not sure.  Split owners confuse a Vanagon  with a
Chrysler minivan and think I'm waving because their engine is on fire, or a
wheel fell off.

Tom