06-08-2015, 06:12 AM
When I have my Garmin Zumo 660 mounted, I can compare speedo to GPS speed.
Until approx. 80 kph, my speedo is about 2-3 km above gps. Then the gap starts to increase.
From about 110 kph it's constantly 10 km above gps, up to the limiter. My CB runs into the limiter at speedo 190 kph, gps shows 179 kph.
I thought, this offset is on purpose. Speedos may show more but never less than real speed.
Until approx. 80 kph, my speedo is about 2-3 km above gps. Then the gap starts to increase.
From about 110 kph it's constantly 10 km above gps, up to the limiter. My CB runs into the limiter at speedo 190 kph, gps shows 179 kph.
I thought, this offset is on purpose. Speedos may show more but never less than real speed.