The point of a limit is that it's a number that is illegal to exceed. We have sort of forgotten about that notion because we all ignore speed limits wholesale (

The point of a limit is that it's a number that is illegal to exceed. We have sort of forgotten about that notion because we all ignore speed limits wholesale (or treat them as recommended speeds). "Inefficient" doesn't get there, and also, on an open road, 85 is fine. Lots of other charges are available for someone going 85 on a crowded road.