Sat Nav Check

[VauxVeteran]

Anyone got a unit that tracks the car speed? if so could you see if it matches up with the speedo, thx.

[Gsi3.2]

our tomtom doesn't match the speedo..at an indicated 90 mph the gps speed is 83mph, so the speedo overreads..

[ed taylor]

Yes our tom tom shows a higher speed than the speedo. might not be a bad thing if the car,s speedo is set slower than correct.

[BigLad]

Ive got tomtom and at an indicated 70mph on speedo the satnav says 67, the satnav using GPS is the more accurate.

[VauxVeteran]

Phew, thx guys it's not only mine then, I'm showing 4mph out, I think it's the nav that's slower though, pretty sure if I'm doing 70 on the clocks it's only showing 66mph.

[fireblade]

My TomTom is always about 3MPH slower than my speedo, oddly my snooper is always 1mph different than my tomtom
From memory I think a speedo is allowed to be up to 10% fast but cannot be slow by law i.e 70mph indicated is ok anything from 63mph to 70 mph
It is not allowed for a speedo to show 63mph when actual is 70mph
All my old Fords were always 8% fast(mondeo,c-max) Veccy is a very close match to actual speed

[sonic]

At 70MPH on the speedo my TomTom says 66MPH.
Your OK VV!

[G.O'Rilla]

I have a pogo (ex origin) GPS camera locator - same results as Sonicboom

[neilshaw1980]

My navigon sat nav shows 5mph slower than speedo. Thats with 225/45/17 tyres.

[SJG]

Speedos have to err on the side of caution so they invariably overread. The GPS speed is correct.

Edit: what fireblade said.