My GPS, like most any other made anytime recently, gives me a readout of my exact current
speed, accurate to 1/10 MPH.  In that regard it is just like a car speedo, except a LOT more
accurate.  In addition, it keeps track of my actual course and gives me a lot of other info,
such as average speed, etc.  It also estimates distance and time to my next waypoint at my
current speed, and these may be subject to the "as the crow flies" errors you mention.  The
direct MPH readout is not.

Bill

----- Original Message -----
From: "Loren A. Busch" <lbusch@IX.NETCOM.COM>
> Be careful before you rely on your GPS to check your speedometer.
> Depending on the make and model of GPS, you may be getting distance as
> 'the crow flies', NOT actual road distance.