I ride a motorcycle and bikers extend their arms towards the pavement when we pass other bikers, bus drivers wave to bus drivers, truck drivers wave to truck drivers etc. How about Mustangs wave to Mustangs, F150 wave to F150(you get the idea) using some kind of wireless signal on the highway, maybe they could flash the headlights or signal lights or do something cool/unique like the turn one light on at a time going from the drivers side to passenger side(I know that would take lots of wiring and not be currently possible).