Buick 2007 LaCrosse Owner's Manual page 202

There is also a retroactive trip odometer function
that performs the following for each trip odometer:
•
If the vehicle's speed has exceeded 3 mph
(5 km/h) during the current ignition cycle, this
function will set the trip odometer to the
distance driven during the current ignition cycle.
•
If the vehicle's speed has not exceeded 3 mph
(5 km/h), this function will set the trip odometer
to the distance driven during the previous
ignition cycle plus the distance driven during
the current ignition cycle.
Press and hold the set/reset button on the uplevel
vehicle or the trip/odometer button on the base
level vehicle for three seconds, then release
the button. The retroactive trip odometer value will
be set into the currently displayed trip odometer.
Time Elapsed (Uplevel Only)
Press the trip/odometer button until TIME
ELAPSED :00 displays. This mode is like a
stopwatch, in that you can clock the time it takes
to get from one point to another. Each of the
fields for the hours, minutes, and seconds are
two numeric digits.
202
Once TIME ELAPSED :00 is displayed, press the
set/reset button on the uplevel vehicle to start
the timing feature. Press the set/reset button again
to stop it. If you will be starting and stopping
your vehicle, during a trip for instance, the TIME
ELAPSED feature will automatically start timing
where it left off when you last stopped. To reset it,
press and hold the set/reset button for about
1.5 seconds. The display will return to zero. Press
the trip/odometer button to exit from the TIME
ELAPSED display.
Average Speed (Uplevel Only)
Press the trip/odometer button until AVERAGE
SPEED displays. This mode shows the average
speed of the vehicle in miles per hour (mph)
or kilometers per hour (km/h). This average is
calculated based on the various vehicle speed
recorded since the last reset of this value. To reset
the value, press the trip/odometer button to
display AVERAGE SPEED, then press and hold
the set/reset button on the uplevel vehicle.
The display will return to zero.