Speedometer error factor

Z

Zed Five

Senior member
Anyone know roughly what the 'error factor' is on a E89 for reported speed v actual? BMWs of old were typically pessimistic (30 shown = 27/28 actual)

Anyone know re the E89? Just wondered what the tolerance will be for Speed Cameras/Speed guns? - I notice that now the weathers nice there are move 'men with speed guns' happy to earn their living standing getting a tan...
 
Motorway cop mate told me once they allowed 10% +2mph.

If you have a Sat-Nav can you not check your speedo against that?
 
mine was off by 5km at 120, speedo shows 120, you're actually doing 115. I drove woth a Garmin Speedo on top of the dash for years....
 
10% +2mph is the ACPO recommendations regarding whether you will receive a NOIP. The OP's question relates to speedometer readings versus actual speed. A speedometer by law must not read under actual speed and generally a speedometer will be showing 8-10% over actual speed. So if you receive a NOIP stating you were doing 37mph in a 30mph limit the chances are that your speedometer would be showing a speed of 40-41mph at the moment that you were zapped.
 
The amended Road Vehicles (Construction and Use) Regulations 1986 permits the use of speedometers that meet either the requirements of EC Council Directive 75/443 (as amended by Directive 97/39) or UNECE Regulation 39.[15]

The Motor Vehicles (Approval) Regulations 2001[16] permits single vehicles to be approved. As with the UNECE regulation and the EC Directives, the speedometer must never show an indicated speed less than the actual speed. However it differs slightly from them in specifying that for all actual speeds between 25 mph and 70 mph (or the vehicles' maximum speed if it is lower than this), the indicated speed must not exceed 110% of the actual speed, plus 6.25 mph.

For example, if the vehicle is actually travelling at 50 mph, the speedometer must not show more than 61.25 mph or less than 50 mph.
 
Speed check ...

terrified-cat-looks-out-car-window.jpg
 
That gona scare the cr#p out of those pesky flys for sure. :thumbsup:

Interesting to read the regs on the speedo, nice post.
 
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