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trevorap2002 wrote: |
All modern cars have their speedos calibrated at a lower speed, by manufacturer, approx. 5% of actual speed as a safety margin against speeding offences per National Design Rules. Anyone clocking over the speed limit is unable to claim inadvertence as at say 100 kph they would have their speedos showing at least 105+ proving an intent to speed. Although subject to a slight tolerance, also to the negative, your GPS would be the more accurate. Your odo should still be accurate as per manufacturers spec or they could be accused of fraudulent practice. Any discrepancy beyond that is due to non manufacturer spec with regards to wheel diameter. |
johmazz2006 wrote: | ||
Good for you Russel... Think I would rather trust a GPS's speed reading over a suspect speedo reading, if there was a discrepancy between the two, as it does not seem to matter what brand GPS you take a reading from, they all seem to come up with the same results. |
asalmon3 wrote: |
Not sure where of 5% on car speedometers. If you can find a review on the NRMA (RACQ, etc), they usually tell you what the error is for that car.
My 2006 Mitsubishi 380 is doing 95 when 100 is displayed on the speedo. This is EXACTLY what both my CoPilot and Garmin GPS units indicate. I usually drive to the GPS now. Cheers! |
billynibbles wrote: |
The hypotenuse of this triangle would represent the road surface on the slope, so therefore for every 1 meter travelled across the surface of the Earth (the base of the triangle), 1.414 meters have actually been travelled by the vehicle on a sloping road. Thus if travelling at about 70 mph (or kph), the sat-nav may well be telling you that you're only 'doing 50' as this reflects your horizontal speed. |
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