Speed Readout from GPS

hertz · Occasional Visitor Joined: Apr 01, 2005 Posts: 9

Since installing TomTom Navigator 3 on my PPC and using it with a Fortuna Bluetooth GPS Receiver, I have noticed that in my Peugeot 306 the speedometer reading agrees exactly with the speed readout from TomTom. However, if I swap over to my LandRover Freelander, the speedometer reads 5mph faster than TomTom. Similarly, in a hired Nissan Micra, the speedo was also 5mph in advance of TomTom.

Am I correct to assume that the GPS readout is more likely to be accurate, and that the two vehicles reading higher have inaccurate speedos?

Hertz

Oldboy · Posted: Fri Apr 01, 2005 5:47 pm Post subject:

Yes. It is quite normal to find that the speedo 'reads' faster than your true speed. The GPS unit will read correctly as long as you are travelling on a straight road, and not going up/down a hill.
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Richard

TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120

Hoppy · Posted: Fri Apr 01, 2005 6:28 pm Post subject:

In my Civic the speedo reads the same as the GPS upto about 35 mph after that my speedo reads between 5 and 7 mph faster than the GPS.

Oldboy · Posted: Fri Apr 01, 2005 7:57 pm Post subject:

That seems about typical of our Civic. Manufacturers are allowed a tolerance of 0 to -10% true speed of the indicated. In theory you should never need to be breaking the speed limit?!!?
_________________
Richard

TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120

Darren · Posted: Fri Apr 01, 2005 8:47 pm Post subject:

The law states they must either be 100% accurate or up to 10% over hence manufacturer err on the side of caution.
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Darren Griffin

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