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    So I have heard that your cars speedo isn’t always accurate for example if my speedo said I was travelling at 37mph but it was actually 33mph would the speed camera pick up the correct or incorrect speed? Just curious as I know speed cameras have a rule of 10% of speed plus 2mph for speedo error!

    Thanks in advance!😊
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    (Original post by Key97)
    So I have heard that your cars speedo isn’t always accurate for example if my speedo said I was travelling at 37mph but it was actually 33mph would the speed camera pick up the correct or incorrect speed? Just curious as I know speed cameras have a rule of 10% of speed plus 2mph for speedo error!

    Thanks in advance!😊
    Cameras must be accurate and calibrated to a national reference standard.

    The camera is certified as true and correct whilst your speedo is allowed errors of up to 10%. That is not to say your speedo is incorrect though, just that in a court of law, an allowance is made for possible error.
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    (Original post by Key97)
    So I have heard that your cars speedo isn’t always accurate for example if my speedo said I was travelling at 37mph but it was actually 33mph would the speed camera pick up the correct or incorrect speed?
    Speedos cannot under-record your speed (unless you've changed wheel / tyre sizes). They typically read a little high - you can use your phone's GPS to get a more accurate speed reading.

    There is no practical way for a speed camera to know what your speedo is reading.

    Just curious as I know speed cameras have a rule of 10% of speed plus 2mph for speedo error!
    Don't count on that.
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    (Original post by Key97)
    So I have heard that your cars speedo isn’t always accurate for example if my speedo said I was travelling at 37mph but it was actually 33mph would the speed camera pick up the correct or incorrect speed? Just curious as I know speed cameras have a rule of 10% of speed plus 2mph for speedo error!

    Thanks in advance!😊
    Speedo's are built to over-read, most of the time by around 10%.

    In the eyes of the law: as soon as you go 1mph over, you should get a speeding ticket. The 10% + 2mph is just a guideline for officers, but does not have to be enforced.

    This thread should be in the Cars and motoring forum. I'll just tag AngryJellyfish to get this moved over there
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    Thank you everybody for all of your help it is much appreciated 😊 I used the GPS system and it’s says I’m travelling at 28mph when my speedo says 30mph and when my speedo says it’s 37mph my GPS says I’m travelling at 34mph. Fingers crossed this is true!!! 😊
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    (Original post by Key97)
    So I have heard that your cars speedo isn’t always accurate for example if my speedo said I was travelling at 37mph but it was actually 33mph would the speed camera pick up the correct or incorrect speed? Just curious as I know speed cameras have a rule of 10% of speed plus 2mph for speedo error!

    Thanks in advance!😊
    From a quick check on Wikipedia, the UK laws regarding speedometer calibration are as follows for actual speeds between 25mph and 70mph:
    • The speedometer must never show less than the actual speed (in other words, you can't speed by accident).
    • The speedometer must never show more than 110% of the actual speed plus 6.25mph.

    This means that if your speedometer showed 37mph, you could have actually been doing anything between 28 and 37. It's unlikely that the speedometer will be out that far, but speedometers generally over-read a little to allow for things like tyre wear.

    Speed cameras pick up your actual speed, not what the speedometer says. But your actual speed is never faster than your speedo, so you have no excuses! If you really want accurate readings, use GPS because it isn't affected by wheel size and tyre wear.
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    I have a digital speedo and it's 3-5mph too fast (based on GPS speed). It's quite annoying really.
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    It's worth being aware that GPS speeds are not necessarily accurate either.
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    (Original post by CurlyBen)
    It's worth being aware that GPS speeds are not necessarily accurate either.
    I was concerned about this as well (i.e. I shouldn't rely on it being correct). According to owners' forums the speedo in my model is calibrated to over-read by about 5mph in the factory so my GPS doesn't seem to be causing me to speed.

    If I go at 30mph (by speed) in a 30 I've always got someone right up behind me. I know that happens anyway because people routinely speed in a 30 limit, but it seems to happen more in this car.
 
 
 
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