That famous road into Monument Valley, from the north in UT, is heavily patrolled, and the speed limit is 45ish...thus the low go.
Our '02 VetteVert saw triple digits many times on our trip, including an hour+ of 140, while set on cruise, in NV. One can cover some ground at that speed and backing down to 85 was like we parked, lol! We did not see another vehicle in that hour...
Hit 170 observed for a brief stretch in southern UT, (the car just flowed & it was matted for a few mins to get to that speed), and later in trip doing 90ish, we got a blue light flash and a wave from a MT state cop, hiding in the median on I-15 in nw Montana, but no stop. Lucky, and we got no tix the entire 13,000 miles in 36 states and 6 provinces.