Just done a little bit of research and the speedometer is erred on the faster side, by law they are not allowed to show you a slower speed than you are actually doing.
Interesting that tyre wear is a factor in speedo accuracy. http://www.drive.com.au/motor-news/...ometers-and-speed-cameras-20120412-1wsqp.html
When I drive past those speed cameras that tell you your speed, I check my speedometer. My speedometer generally reads 2-3mph more than the camera. When I was young, Autocar used to publish the accuracy of speedometers of cars at various speeds. In general, the speedometer always overstated the true speed. Autocar also used to publish the real-world fuel consumption figures too (again at various speeds) but I don't think they even do that now. The government fuel consumption figures can over-exaggerate the fuel economy of small low-powered cars by as much as 30%. For larger cars, the real world figures can actually be better than the official figures!
Well I think that speeding fines and parking tickets should be outlawed until such time as those offences can be enforced against the drivers of vehicles with foreign number plates, such from within the EU. And that won't be happening any time soon.
They tell you what speed you are going, irrespective of whether you are under or over the limit. If you are not over the limit the digits are in green. If over the limit, the digits are in red.
There was an article about that on the Telegraph website yesterday. Not certain how practical the enforcement will be.
There have been cases of foreign drivers getting done for serious driving offences but nothing gets to court, as far as I know, because the culprit just skips the country. Then he/she comes back in with another forged drivers license. I was talking to a driver one day and his company checked their drivers records to find 12 of them (Polish) all had the same numbers but different photos on the cards. I often wonder why governments in Europe do not share more details. Perhaps things may change now.
I used to enjoy the average speed cameras that were in use across Scotland whenever there were roadworks on the major arteries, which was often.
Anyone come across this new phenomenom. "Smart" Motorways! The section I saw today was beset by roadworks and average speed cameras set to 50mph for mile after mile. http://www.highways.gov.uk/roads/road-projects/m6-junction-10a-13/
They are turning a stretch of the M60 into a smart motorway, the road works are absolutely horrendous but hopefully the end result will be worth it.