RE: GPS distance.

This is because the GPS calculates the straight line distance between
the starting and ending points.  Although it calculates its exact
location several times a second and uses that to determine its speed, it
does not store the incremental distances between locations, which it
would need to calculate total distance.  Hence it can plot your trip,
give you the speed, current location, but distance from starting is
always wrong (compared to how you got there)

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Loren Busch
Sent: Friday, August 04, 2006 10:27 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Reasonable cruising speed?

 RE: The speedometer and odometer are fed separately.
Actually, they are both fed from the same source, the speedometer cable.
But the odometer is a direct physical connection to the cable.  The
speedometer dial that you can see is driven/moved by induction through a
spinning magnet inside an aluminum cup, consequently the speedometer can
vary, no direct connection.  The odometer is counting the turns of the
wheel
in the case of the 2wd Vanagon and the inaccuracy can only come from
tire
diameter being different from the factory spec and not turning at 805
revolutions per mile.
I happen to be lucky, my odometer and speedometer are in very close
sync,
both read about 2% high based on measured mile courses on the highway.
BTW,
although my GPS seems to provide accurate speed, it ends up way off on
distance, usually many miles low over a couple of hundred miles.