Speedo or GPS

[SuperSel]

Hello all,
just a quicky really.

Which is more accurate 1, The speedo in a vehicle or 2, The indicated speed on my Tomtom.

There is only about 5/6 Mph difference between them but with 9 points on my licence I'd be interested to know.

Thanks in advance.

Selwyn

[Toureman]

Your question has already been answered about 20 times on answerbank

[TCL-MUMPING]

Speedometers may not show a speed lower than the true speed but they are allowed to show a speed up to 10% higher than the true speed.

[Panic Button]

OK Toureman, what were the answers to those 20 questions?

[Buenchico]

As TCL states, speedometers must be manufactured in such a way that they can never 'under-read' but may (within certain tolerances) ''over-read'. This allows for such factors as wear n the tyres and stretching of the tachometer cable to be taken into account.

SatNavs are generally far more accurate. Some people suggest that you need to take account of the time delay for the satellite signals to reach your car (and be to processed) but the satellites are only 22, 000 miles up and radio signals travel at 186,000 miles per second, so the delay is negligible.

Chris

[Toureman]

Here's a few, with more search words there's probably more...............

http://www.theanswerbank.co.uk/Search/Sponsore d.asp?SearchText=sat+navs-speedometer&searchTy pe=site&x=14&y=9

[dl56uk]

I have a Binatone Carrera 350 and when it says I'm traveling at 56mph , the speedo on my car is about 63 mph. I think a check on a rolling road at a garage when you next get a M.O.T will tell the true measurment

[rojash]

If you already have 9 points on your licence, then the sensible thing would be to forget which is more accurate, and drive according to whichever shows the highest speed - that way you know you're safe.

[Disco Fever]

The Tomtom signal will have to travel from your car to the satellites above you and back again so the Satnav will be out by about 10% as mine is....