We discovered the REAL bus-to-bus wave last summer.  We were vacationing in our '88 in the Finger Lakes area of upstate NY near Ithaca, home to Cornell University and many, many still successful hippie comunes (sp?).  Motoring at a sedate 50mph enjoying the warm summer afternoon and the view of Lake Cayuga, approaching in the other lane comes a true multi-color, peace sign adorned, 65 ish VW bus being driven by two tie-dyed, kerchief wearing, ancient hippies (my age for darn sakes).  Beep-Beep, I look to see both of them jesturing with both hands.  They were making a "VW" with overlapping fingers (make a Vee with the 1st and 2nd fingers of both hands. Overlap them at the inner joint of each index finger.  Voila,  a VW in correct logo presentation.   My kids age 9 and 12 both went wacko.  Since then we have been passing along the "VW" sign whenever possible. 

Gary