GPS should be more accurate It is a known fact that most speedometers have an error on the positive side : they always show a speed which is slightly higher that the "actual " speed of the vehicle. You can verify this by checking the auto-reviews done by expert testers, who use sat-based instruments (more complicated form of GPS) to do the speed testing.
(some road test results I remember : Scorpio had an odo reading 160kmph, when it was actually doing around 153kmph; Mercedes doing 187kmph actual on a speedo read of 190kmph)
So, your GPS reading is probably giving the more accurate speed. |