My 1986 S-10 Blazer's speedo stopped at 85mph, even though the needle could keep going and end up hiding behind the rest of the plastic of the speedometer.
It was actually more of a challenge to see if I could make the needle disappear...
I always thought it stopped at 85mph because the car couldn't physically go faster than than (aerodynamically). That's interesting that it was actually because of obscure government regulation...