I agree, it seems like a basic feature that is simply missing from the basic autopilot. Not sure about enhanced or FSD as I have not tried those. Generally the speed limit updates on the visualization with pinpoint accuracy, but while in autopilot, it does not adjust and I need to manually use the wheel or touch the speed limit sign to adjust. This applies to upward or downward adjustment. It seems there should be a setting to enable to track the speed limit (also should account for the offset).