Speedometer Question - Curious

[majik755]

I've noticed that the dash speedometer and the heads up display are not exactly the same. A few mph difference. Any idea which reading is more accurate. I'm assuming the digital readout of the heads up is the most accurate and set my cruise control and reaction to law enforcement sightings based on that...

Anybody know for sure?

 

[XLR KEN]

I believe part of your question is a good indication of the answer.

A digital read out has increments of single digits, whereas an analog dial is somewhat an indicator based on visual alignment. If you move your head to either side on the analog dial, it changes the reading. Also, the speedometer is a press-fit on an stepper motor in the cluster. If you stick it on the spindle a little off-scale, it changes the reading.

A good check would be to run a portable GPS unit that has relative speed readout (i.e. Garmin) and coorelate it to the heads-up display.

XLR KEN