Regarding speed signage recognition. When I had my previous Clio and Capturs, the camera would read the sign, display it and keep the display up (flashing if you exceeded that speed) and change when it next encountered another sign.
The Jazz though reads a sign, displays it.. but then it clears the sign after a few minutes and doesn't display again until it hits another sign. So, it is only displaying the last seen sign for a short period. Is this normal?
Mine does this too.but as you say its displayed for a ' a few minutes' , or at least for a reasonable length of time. Personally I think this is a sensible way of doing it. Eventually the absence of a speed limit sign reaffirming the speed limit, or something different becomes a less reliable indicator of the current limit. The chances increase that a sign was missing or obscured , or that the system failed to read it . In effect by switching off the system is saying, ' I'm no longer sure ,maybe you should check for yourself.'
In the Uk there is a a general ruling that if there are lamp posts the limit is 30 mph unless there are speed signs to the contrary. Lower or higher. So within a town you may travel miles within a 30 mph limit without ever seeing a speed sign, You are meant to know by the environment and presence of lamp posts (even if not lit) . You can argue that if the car constantly displayed 30 mph , then its at least erring on the cautious side. Even if its wrong. But what if you enter town from a higher speed limit, and for some reason the first, and possibly only 30 mph sign you will pass is missing or obscured, and not read. The system would continue to display the last limit it read , and you could travel miles in a 30 limit with a higher speed shown by the car. . By switching off eventually it at least prompts you to reassess the situation for yourself (, although you should have been doing this anyway.) I also regularly check what limit is shown on the sat nav although this is not always reliable . If you are worried about exceeding a 30 mph limit because its not displayed by the car , set the speed limiter.
Things can be even more confusing for the system in some countries. The urban speed limit applies between the village/town name boards at the start and end. There may not be a speed limit sign at all, or lamp posts.