A GPS is as accurate at calculating your vehicle speed as is a 'certified'
speedo in a police car.  So when the speedometer in my 2006 Liberty was
registering 107 kph when the GPS was showing 120 kph, I mentioned this at my
next service interval.  The mechanic came up with a relatively easy fix.  He
re-programmed the computer to make it think I had different sized tires on the
car.  He got it dead on.  However, the odometer still registers less kilometers
than the GPS records.  I have verified the GPS odometer with the markers along
the highway.

Can anyone confirm that  electronically altering the speedometer reading would
not necessarily change the odometer as well?  

Thanks