Seriously? Your average speed was 123mph? I'm surprised that the CX-5 will even go that fast let alone average that speed over any distance.
I uploaded this pic earlier in another thread - GPS measuring is more accurate then the speedometer. 223kmh is 138.5mph and the speedometer will show around 140-142mph it's always a bit higher.
My bumper baby sometimes run up to 143mph (depends on his mood and the surrounding conditions-everyday a bit different) then the speedometer show around 146/147mph.
Usually I don't take pics on this speed ;-)
Cheers 101