Speedo inaccuracy/safety factor Vs. Odo reading

[mike_nofx]

Originally Posted by Nashy86

Try this: Sit on the freeway with the cruise control set right on 100km/h, then on your trip computer bring up the "average speed" and re-set it.
Assuming your speed stays the same (hence cruise control must be on) then the measurement for average speed will be the "real speed"

A few years ago when I was working for Ford, I had a brand new Territory Ghia for a long drive over a weekend and I tried the trick above. When the speedo needle said 100km/h the "average" measurement said 96km/h which reflected what the freeway overhead speed check told me, and also reflects the 4% deviation that is programmed in from factory.

Based on that, I would suggest that if the "average speed" is measuring rel speed, then the ODO would be measuring the real distance.

Tried this on the BF this morning.

Sat spot on at 110km/h for a few Km, reset the average speed and it averaged 106km/h for the duration.

[smally289]

As above, tried it on the BA work hack. 115 on the speedo, set the cruise and reset the average speed. Came up as 110 which is exactly what the Navman GPS and the one on my phone indicate.