Ford 1999 Crown Victoria Owner's Manual page 19

If "CO" or "CS" is displayed, there is a problem with the fuel indication
system and you should contact your dealer for service as soon as
possible.
AVG ECON (average fuel economy)
Select this function to display your
average fuel economy in liters/100
km or miles/gallon.
If you calculate your average fuel
economy by dividing miles traveled by gallons used, your figure may be
different than displayed for the following reasons:
your vehicle was not perfectly level during fill-up
differences in the automatic shut-off points on the fuel pumps at
service stations
variations in top-off procedure from one fill-up to another
rounding of the displayed values to the nearest 0.1 liter (gallons)
Press the RESET control while AVG
ECON is displayed to reset the
function.
The average displayed is the average
since the last reset.
TRIP A and TRIP B
These two functions allow you to
see how far you have traveled since
you last reset. Trip A and Trip B are
completely independent and must
be reset individually.
Instrumentation
DIST TO AVG
EMPTY ECON
TRIP TRIP
A B
RESET E/M
DIST TO AVG
EMPTY ECON
TRIP TRIP
A B
DIST TO AVG
EMPTY ECON
TRIP TRIP
A B
AVG
SPEED
SELECT
AVG
SPEED
AVG
SPEED
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