I don't know what it's like now Duncan but when I lived in the Territory you waved at EVERY car on the road (well highway anyway, not in town) and 90% of people returned it.
I even tried to give the people I overtook a wave because I knew that I just scared the shit out of them by backing off as I passed. (I had a tickled 308 and two hot dogs, no muffler, quite advanced timing and flames out the back on a big back off )