I've tested GPS on many cars and a couple of aircraft, I can say that they seem very accurate. I of course have not compared these readings with readings from a radar gun, which would be the only accurate way of testing them.....
I would trust the GPS over a speedometer any day, providing you're in an open area and measuring the result over a period of a few seconds or more...
JC
I would trust the GPS over a speedometer any day, providing you're in an open area and measuring the result over a period of a few seconds or more...
JC