I encountered a speed limit sign that had been altered by somebody. Just the typical prank spray paint change from 35 to 85. Evidently, speed assist believed it because the little gray line on the speedo suddenly moved to 85. I laughed that it was actually confused like that. So I turned around to try get a picture of the sign, but the next time I drove by the gray line didn't move. I'll have to try again some other day. I did have a slight concern that if AutoPilot had been on it would have increased the speed to 85. With this car I could easily be at 60 or 70 before I realized what was going on and stepped on the brakes. Granted, I wouldn't plan to use AutoPilot on back roads, but what if the prank was on an interstate changing from 65 to 85 (or 165 like I have seen).