MPH Accuracy

[rcballard]

How accurate is the mph readout on the XXL 540?

 

[dhn]

The GPS is accurate as it does not need to worry about factors such as tire size, etc that affect speedometer readings (which will show up to 10% HIGHER than the true gps reading).

 

[Andy_P]

On a flat straight road at steady speed, it is VERY accurate (something like 0.2 mph accuracy).

It will always be far more accurate than a normal speedometer. the reason being that the car manufacturers are allowed to have their speedos showing upto 10% too high, but they must not read LOW at all. Therefore they are all made to read around 5% fast, to keep in the middle of the tolerances.

The only problem with the speed displayed on the TomTom is the update frequency. The display only changes about once per second, so the figure shown "lags" a little if you are accelerating or decelerating hard.