So I observed the behavior of mine for awhile this afternoon, and here's what I think is going on. The display is supposed to show the limit for the speed zone you are currently in. If you exceed that limit by a little bit, it turns yellow. If you exceed it significantly, it turns red with an exclamation point. And if you were really flagrant it stays that way for awhile, maybe until you have passed into a different speed zone at legal speed at least once. Maybe more, I haven't figured out the algorithm completely. If you live on a street where the speed limit is 25, it may seem to never go away. And the guy whose screen says 20 - your Ram thinks you blew through a school zone, man...