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Originally Posted by nstg8a
Agree 100% and it's probably one of the reasons I use my gps for speed more than I use my speedo.
Mind you, how accurate are gps' really?
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A guy at work has been really into GPS devices since the early days, and he has thick books on the subject of accuracy (or variability thereof).
Our work Prados all have a "BigMate" system in them that tracks vehicle location and speed, and some people have been pinged wrongly for "speeding". The most memorable was one guy who got a serious "please explain" for doing 170kph.
Then someone thought to check the log to see when he did it, and the graph showed his speed go from a steady 100kph, to shoot up to 170kph, and then drop back down to 100kph, all within four seconds. Now, either someone has fitted rocket engines to that Prado, or something is wrong with the GPS...
I've even noticed on the GPS in both our Triton and my Celica (a Navman and a TomTom respectively), sometimes go from a strong signal to no signal to a strong signal again. The speed, in the meantime, will sit on some reading which is obviously wrong, and then within seconds snap back to "normal" again.
GPS is accurate...but it's still subject to slight variations, and when you are only allowed a kilometer or two either way, it's a worry.
Cruise control is another question...yes, it's wonderful...but it too isn't dead accurate. Our G6E varied slightly as you went up and down hills, the one in our Triton does so too according to the GPS. These are both very recent model cars,so it's not like they're worn out old dungers.
Either you want people to get where they're going and for traffic to flow efficiently...or you are encouraging everyone to sit on 90kph just to be absolutely sure they won't wander slightly over the limit on the highway.