Any time I get to thinking my Jeep is a rough ride on the highway, I'll spend 8-10 hours in the back country with it, and then when I come back on road it feels REAL SMOOTH.
On the way up in the mountains there are a lot of washboard roads. Driving on them reminds me of the "electronic" football game my brother & I got for Christmas in '66. The one that would vibrate the metal field and the players on plastic bases with little plastic whiskers underneath would shuffle around the field pushing a felt football.
(If this seems odd, it was back when we had a b&w TV, before 8-tracks, before cassettes- I don't know why they called it electronic.)