The speedometers are only "calibrated" in a loose sense.  As others have
said, the
number on the speedo face is the number of turns of the cable to register 1
unit
on the _odometer_.  Interestingly, VDO uses only two different parts for
metric
and mile speedometers -- the odometer drive gears, with either ten or sixteen
teeth.  Close enough, I guess.  The Syncro speedos have two different parts
too,
making a total of four speedos.  There are other numbers on the speedo faces
as well -- like "805", "810", "800", but I suspect that they are all really
"800"s.

If you want to really be accurate, VDO sells a $100 electronic speedometer
that
reads pulses off the speed sensor (Vanagons don't have one, but VDO sells a
$40
sender too).  You push a button, drive one "unit" and push it again.  If you
change tire sizes, or move to Canada, you simply recalibrate it.

Malcolm