Hummer 2008 H2 Owner's Manual page 201

Trip Odometer
Press the trip/fuel button until TRIP displays. This
display shows the current distance traveled in either
miles (mi) or kilometers (km) since the last reset for the
trip odometer. Pressing the trip odometer reset stem
will also display the trip odometer.
The trip odometer can be reset to zero by pressing the
set/reset button while the trip odometer is displayed.
You can also reset the trip odometer while it is displayed
by pressing and holding the trip odometer reset stem.
The trip odometer has a feature called the retro-active
reset. This can be used to set the trip odometer to
the number of miles (kilometers) driven since the
ignition was last turned on. This can be used if the
trip odometer is not reset at the beginning of the trip.
To use the retro-active reset feature, press and hold
the set/reset button for at least four seconds. The
trip odometer will display the number of miles (mi) or
kilometers (km) driven since the ignition was last turned
on and the vehicle was moving. Once the vehicle begins
moving, the trip odometer will accumulate mileage.
For example, if the vehicle was driven 5 miles (8 km)
before it is started again, and then the retro-active reset
feature is activated, the display will show 5 miles (8 km).
As the vehicle begins moving, the display will then
increase to 5.1 miles (8.2 km), 5.2 miles (8.4 km), etc.
If the retro-active reset feature is activated after the
vehicle is started, but before it begins moving, the display
will show the number of miles (mi) or kilometers (km)
that were driven during the last ignition cycle.
Fuel Range
Press the trip/fuel button until FUEL RANGE displays.
This display shows the approximate number of
remaining miles (mi) or kilometers (km) the vehicle
can be driven without refueling. The display will show
LOW if the fuel level is low.
The fuel range estimate is based on an average of
the vehicle's fuel economy over recent driving history
and the amount of fuel remaining in the fuel tank.
This estimate will change if driving conditions change.
For example, if driving in traffic and making frequent
stops, this display may read one number, but if
the vehicle is driven on a freeway, the number may
change even though the same amount of fuel is in the
fuel tank. This is because different driving conditions
produce different fuel economies. Generally, freeway
driving produces better fuel economy than city driving.
Fuel range cannot be reset.
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