Accuracy of Speedo

pbu50w · Posted: Wed Oct 27, 2004 6:08 pm Post subject: Accuracy of Speedo

Does anybody know or has anybody tested the accuracy of the current speed readout on the TTG. The speed indicated on mine is a good 10% lower than my car speedo. I'm running on update 4.4

lbendlin · Posted: Wed Oct 27, 2004 8:57 pm Post subject:

The GPS speedo is always much more accurate than the car speedo. Your car is required by law to show about 4 mph more than you actually drive.
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MrRubberGloves · Posted: Wed Oct 27, 2004 9:11 pm Post subject:

If you were stopped by the police for speeding and your TT Go was showing 30mph yet your car speedo was showing 40mph what reading would the device the coppers were using be more likely to show, 30 or 40mph?

lbendlin · Posted: Wed Oct 27, 2004 9:42 pm Post subject:

30 minus the tolerance they have to give you. (usually ~ 3)
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Tim Buxton · Posted: Wed Oct 27, 2004 10:01 pm Post subject:

lbendlin · Posted: Wed Oct 27, 2004 10:05 pm Post subject:

funny enough in the US the speedos in the car are dead on with the GPS speedo. This is rather a european thingie, and may even be different from country to country. Someone from the UK can certainly come up with the name of the law
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Tim Buxton · Posted: Wed Oct 27, 2004 10:13 pm Post subject:

The law here says that a speedo must be in the range of 0-10%, and that it *cannot* read under the actual speed. Therefore most manufacturers set them to read a bit high just so that they won't read under. There is no 4mph law!
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Zuke · Posted: Wed Oct 27, 2004 11:10 pm Post subject:

The TTG speed readout seems to be averaged or smoothed over the last few seconds. It's therefore not an accurate 'spot' reading unless you are driving at constant speed, and can be well wrong during hard acceleration or braking. Handheld GPSrs, like Garmins, do give a better spot value, which will always be accurate compared to the vehicle instrument, and is a good way of calibrating yours, (until the tyres wear a bit).

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