Which is more accurate?

[mdhazell]

Apologies if this has been covered before but which gives me a more accurate indication of my current speed, my TomTom One or my car speedo?

My TomTom normally shows me as going 5% slower than the speedo. I usually work to the speedo as this prevents any embarassing cameras flashing at me but was wondering what people thought.

Thanks,

Mark

[PaulB2005]

Been covered many times.....

Sat Nav is more accurate. All mechanical speedos have to over read the speed (i.e. read higher than the actual speed) so you can't blame the speedo for being over the limit when you thought you were under or on it.

[mikealder]

Go with the GPS speed as it is far more accurate than a car speedo - GPS is best when travelling in a straight line, but the difference in accuracy when cornering is small to be honest. I set Cruse Control based on the GPS speed rather than the vehicles speedo - Mike

[Wazza_G]

The GPS is more accurate as it reads the satellite signal approx 50 times a second, it's also not affected by different tyre sizes or other factors that can affect a mechanically driven speedo such as temperature.

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