[hnick]

Or their idea thereof... when I use my GPS it surprises me how low my car actually reports my speed compared to reality. It probably explains all the slow drivers in the right lane over here.

Go on the M4 though and 10 over is too slow for many!

[nradov]

How are you checking the real speed? Most GPS receivers display more accurate speeds than car speedometers do.

[hnick]

I'm assuming the GPS is accurate. I've driven through speed traps with it just on or over the limit and been fine. My car on the other hand is reporting around 5 kmh higher, depending what angle I'm holding my head at.