Australia Design Rule 18.5.1.1.2 states...

18.5.1.1.2. indicate the actual vehicle speed, for all speeds above 40 km/h, to an accuracy of ± 10 per cent.

So, if I my speedo isn't required to be any closer to my actual speed than 10% (over or under), how can I be booked for anything under 10% over the limit?

The pricks have been racking in the money for years with this loophole...look it up on google.

 

My understanding , is that manufacturers have a 10% allowance on speedos that can read higher than actual speed , but not lower . The odometer has to be spot on , for warranty reasons , but have never been able to work out how they can be different .

I have the same 6Km issue on all our vehicles, 2004 Nightrain, 2011 Can-Am Spyder, 2011 Triton and 98 Porsche. 660 Lumo GPS reads 100Km
I cruise on the highway on the speedo at 118 and have never got a ticket

You know your speedo may be inaccurate by plus or minus ten per cent so it's incumbent upon you to take that into account when determining what speed you will drive at. If in doubt, you do ten per cent less than the posted limit.

Interesting also states after 2006 no requirement for a odometer.    So you can now buy cars, that you have no idea on how many Kilometres they have done.

 

 

I would assume they record the milage in the engine management systems. Should be accessible with the appropriate software and cable.