Is speed camera tolerance 4kph ALL the time?

As for accuracy of the speedometer (separate from the odometer) the European Union rules insist that speedos in all vehicles sold in the Union must be optimistic to about 7% or so. That means if a manufacturer wishes to sell vehicles there (and that would be ALL manufacturers no matter where in the world they are!) must comply.So where the speedo would read 100 km/h the actual true speed will be less than that - say, 94 to 97 km/h.There are similar rules in the USA and again in Australia and NZ.
Take a scenario where I am travelling along and get flashed (altho that ain't happening now with new cameras and their infra-red flash units!) and then get the infringement notice in the mail claiming that I was driving at 112 km/h - in actual fact my speedo would have been reading somewhat more than that!Associated with my view of the speedo. unless it is immediately in front of the driver there is a thing called parallax error. The needle may seem to be on the 100 but you are viewing it from an angle.Being interrupted here and have to depart but research the term parallax.cheers

Great work!
Thanks very much for that. Such a shame that the articles I based my opinion on didn't mention any of this. I may well be partly to blame for making incorrect assumptions based on the gist of what they were saying but it would have been nice if they presented the whole story.

I take my hat off to you, for going to the work of checking this out, and to the Police for being fair and proper with respect to this.

Humble pie gladly eaten!

Take this with a grain of salt because I am scratching my head to remember.

I think before there were rules about this many manufacturers of vehicles for the European market had already started doing this from about the time speed camera's were introduced over there. I think the reasoning was to guard themselves against potential prosecution/class action should their speedometers be reading slightly slow. This was also from an article in a car mag or similar so who knows if its accurate.

BTW, more great research on your part, this was the first I knew of it being an actual legal obligation over there.

Incidentally. as an aside, on my last two trips to town I have seen an absurd amount of Police on the road (approx 4 cars in 3km on a couple of occasions). They appeared to be on patrol, not responding to anything in particular, but in fairness I couldn't tell you for sure.

Interestingly because traffic crawls around here at this time of year and there are no places to pass, despite the numbers on patrol I have only seen a couple of cars pulled over and both were just inside a 50km/h zone.

I know my observations are just that, observations of a very limited sample. But if what I saw was a fair representation it would be nice if they tailored their actions better to suit the situation. I can think of a number of places some of those Police could be of more use at this time of year.

Neither of us know for sure, but in my own experience when you see more than one car 'trolling' in a short space, it usually means they're on the look out for somebody in particular. I say in my experience because twice I have seen enough cars to think twice about it (as you did) and both times a short time later all of the cars had converged on a single spot (once a pedestrian, once a car).