After reading an earlier post about MH owners waving, my brother and I decided to do a "wave test" along our route from Vancouver to Northern Ontario in early June. We would wave at every single Class A we saw, no exceptions. Here is what we found:
a) on 2-lane highways, the rate of "wave return" was about 50% in the USA and 75% in Canada (probably because of slower speeds and the fact that Class A's are rare on Cdn roads)
b) on 4-line highways, the rate of return in the US was about 40%, although that varied with how wide the median was
On our return trip in August, the rates had changed significantly:
a) on 2-lane hwys, the rate of wave return in the US was about 70%, while in Canada it climbed to 95%
b) on 4-lane roads, the rate in the US increased to 60% (70% if there was a smallish median)
c) the rate of wave return on interstates increased dramatically if we did a "pre-wave", i.e. did a preliminary wave at some distance, followed by a wave when the rig got closer. In those cases, the rate of return climbed to about 80% on 4-lanes and over 90% on 2-lane roads.
Nothing like science