Can someone explain to me why my vehicle speed according to my speedometer and my speed according to my GPS/SatNav are out of sync by about 3 km/h? And which is more accurate? Thanks in advance.
In: Physics
In Australia it’s illegal for speedos to read low, but they’re allowed to read high by up to 10%+4km/h. Other countries are similar. So all the cars I’ve driven in far enough to test read high by about 5%. I test by timing the 5km speedo test markers on some roads which I assume are accurate and the GPS readings seem to match these results.
In other words, GPS is more accurate than a speedo for legal reasons. Interestingly, while speedos read high, odometers are much more accurate but read very slightly low. I’m guessing there’s more law behind that.
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