I see that more modern satnavs than mine constantly show the speed limit for the road you are driving on. Brilliant! Cos as ALBF says above, you only have to have a lorry obscuring the sign and you are scuppered. All well and good - if they are correct - they are not always, even when kept updated. I have just driven both ways through France, and my GPS was not always correct. It is also difficult to change speed quickly - there was one occasion when the change from 130 to 110 was made half way down a pretty steep hill - with no warning beforehand. If you just happen to be overtaking at the time ... voila, caught on camera with no intention to speed, bu not way of not doing so either. And yes, sadly I did get a fine - I presume when it changed from 110 to 90 with no warning as I was overtaking. Even when trying hard not to speed, it can happen. I was cruising downhill well below the permitted speed limit, with foot OFF accelerator - if I had not kept a careful eye I too would have been unintentionally speeding ... just because of the gain in speed due to the incline. I try hard not to speed, but there are often extenuating circumstances.