Both the 320 and the 60CS have showed the right speed for my van, so I suspect it may be your car. My Honda is off the road because we cannot afford to insure it (damn Ontario insurance weenies), so I have not check it against a GPSr. I however have previously check the Honda odometer against a measured kilometre, and the odometer measures a shorter kilometre which would translate into a higher indicated speed. Honda plot, or cultural calibration difference? You are welcome to borrow my GPSr and check, maybe when we are racing to Ambitious Snorkeler. ......G Gordon Campbell wrote: >It's been consistently a 5 km/hr difference no matter what the terrain >or the speed of the car. I've been assuming that Honda had intentionally >set the speedo high to make you think you're going faster than you are. > >Cheers, >.....G > >On Mon, 2004-08-16 at 12:28, Hoover wrote: > > >>On Mon, 16 Aug 2004, Gordon Campbell wrote: >> >> >>>Does anyone know how reliable the speed reading on a GPS is? My sTrex >>>consistently insists that my car is travelling at exactly 5km/hr less >>>than the speedometer. hmmmm. >>> >>> >>I saw the same thing with Root's old car. I assumed it was a calibration >>issue with the speedometer. I should check again in the new car. Now that >>I think of it, this is more likely related to the GPS receiver not >>including changes in elevation in its calculations. I think it projects >>your position onto its mathematical model of the Earth and measures your >>movement along that. So if you are driving up a hill, your projected >>motion would be slower than what your speedometer says. Or maybe the model >>is not quite parallel to the surface of the Earth in our part of the >>world. I'm just guessing at all of this, of course. >> >>Hoover >> >>------------------------------------------------------------ >>Kingston Area Geocachers mailing list >>//www.freelists.org/webpage/kag >> >> ------------------------------------------------------------ Kingston Area Geocachers mailing list //www.freelists.org/webpage/kag