I had the "privilege" :M of using mine in Utah and in Arizona two weeks ago... Sign or no sign, permission or not!
We were talking our 5er to Mesa to be re-roofed. We left I-15 south of Beaver, onto 20 for a "scenic" drive. Much of my "scenery" was watching the speed drop (sometimes below 20 mph), when the "Fuel Rail Pressure Relief Valve" started lifting on those long, moderately steep roads. It was embarrassing :o and angering :M....But I did get to "test" the "emergency flasers" :R I'm usually "stuck" behind a slower vehicle. This time "I was, the slower vehicle"!