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GPS how accurate
edited November -1
is the MPH/KPH function? Is it consistent?
As a rule, the speed shown by a gps will always be more accurate than that shown by the speedometer on your car; in fact, auto manufacturers set their speedos to show greater than actual, sometimes by up to 5%.
That is my understanding.
This assumes your gps is locking into at least 3 satellites for proper triangulation.
If you do a forum search you will find a number of threads on this topic, such as
thanks, interesting thread. The reason I asked is that I was stopped by a cop a few days ago. I ride a MC and I know that the speedo is about 8 to10 % off so always go by the GPS speed. I had the GPS Cruise Control set at 73 on the highway where there was a 70mph speed limit. The cop said I was doing 82 mph. When I told him I had the cc set at 73, he just gave me a warning, told me to watch my speed and left. I have never had a problem in the past using the cruise control as a speedometer on my bike.