At 09:37 PM 4/13/2010, Kevin Gilbert wrote:
>My Garmin indicates a highway speed about several mph different than
>the speedometer. Do you all think GPS units are accurate?

Within their limits they're extremely accurate.  The speed display
runs behind by a second or more, it's averaged over the last few
seconds, and it will read low if you're not traveling in a straight
line.  Aside from that they should be dead nuts on if you're seeing a
reasonable number of satellites.

Yours,
David