Speed Display on Garmin Map Pilot?

[Prop321]

Hi, I have just bought a 64 plate C250 estate with the Garmin Sat Nav. I have noticed that the speed displayed on the screen is exactly the same as that displayed by the analog speedometer. It also matches the cruise control set speed.

I know speedometers are generally said to read about 10% below actual speed. In previous cars I have owned and used with a stand alone TomTom this has been borne out (i.e the speed displayed on the sat nav has been lower than that on the speed and set fro the cruise control. For example the SatNav shows 28mph when the speedo shows 30).

Is the cruise control setting in my C class lined to the Sat Nav then?

 

[mikrt]

I always thought Speedos read 10%ish over actual, to keep you under the speed limit.

 

[Prop321]

Apologies - I got it the wrong way round. You are right, I was expecting the speedo to read 10% above actual. My query remains though, why is the Map Pilot showing the speedo as accurate? Is the speedo accurate or is the Garmin also reading under?