satnav speed v speedo

Honest John Back Room » Motoring discussion
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Fri 3 Feb 2006 20:07
satnav speed v speedo - Navara Van man
I have noticed that the speedo reads about 3miles per hour less than the speed shown on the satnav. Is the satnav more acurate ?
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Fri 3 Feb 2006 21:10
satnav speed v speedo - autumnboy
yes,

Due to tyre wear, tyre manufacturer to tyre manufacturer tread design differences and speedo mechanical tolerance errors.
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Fri 3 Feb 2006 21:56
satnav speed v speedo - Altea Ego
Satnav is more accurate in a straight line.

Speedos are rarely 100% accurate. Always over read.
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TourVanMan TM < Ex RF >
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Sat 4 Feb 2006 09:30
satnav speed v speedo - Ruperts Trooper
The car's speedo must over-read between 0% and 10% - any under-read is unlawful.

IF sat-nav is more accurate it should read LESS than the speedo.

If sat-nav reads more, then either the sat-nav is inaccurate or the speedo is illegally calibrated.
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Sat 4 Feb 2006 12:58
satnav speed v speedo - Ruperts Trooper
A 1:10 hill will only alter sat-nav calculation of speed by 0.5% so a 1 mph difference at 200 mph might occur for short periods!
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