I know nothing about COMAND, but will comment anyway.

If the unit was calibrated English units, would it read in miles/Imperial gallon? This will increase your virtual mpg by 20%, since there are 1.2 US Gallons in an Imperial gallon.

This might have added to all of your fun...

Ah, the good old days of looking out the window to determine one's postion...

Best Regards,
Jim