We took a short camping/road trip over the weekend and took the Garmin Nuvi along. The speedo on the Fit is dead on: accurate to within 1 mph at 70. Most of my previous cars were off by 3-5mph (indicated high) at 70mph.

 

I was just about to post how mine wasn't dead on. Yesterday with my TomTom 720 Go the speedometer read 2-3 miles over what I was going--I was traveling about 55-60mph.

 

I dont trust GPS for speed, the satelites dont always keep in place (they speed up and brake too catch up, sometimes too much throttle etc). One day i was waitin at a red light, not moving AT ALL, and it showed 2 miles per hour -.- and no this wasnt when the GPS was "loading up". also, some GPS cant really be so precise to the exact foot, at least those for cars. in some cases, its simply because the GPS is still "loading" or trying to pin point your location, at other times its just because its a piece of shayt

 

GPS velocity accuracy is usually stated as 0.1 mph or thereabouts. Speed is measured by doppler frequency shift and not just distance moved. GPS is not as reliable at calculating speed or direction when you're sitting still, but is very accurate when moving at a constant speed for a few seconds.