Cadillac 2007 XLR Owner's Manual page 370

To remove the fuel cap, turn it slowly
counterclockwise. The fuel cap has a spring in it; if
the cap is released too soon, it will spring back
to the right.
While refueling, hang the tethered fuel cap from
the hook on the fuel door.
370
An alternate fuel door
release is located inside
the trunk behind a
panel on the driver's
side of the vehicle. Pull
the handle to release
the fuel door.
CAUTION:
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If you spill fuel and then something
ignites it, you could be badly burned. Fuel
can spray out on you if you open the fuel
cap too quickly. This spray can happen if
your tank is nearly full, and is more likely
in hot weather. Open the fuel cap slowly
and wait for any hiss noise to stop. Then
unscrew the cap all the way.
Be careful not to spill fuel. Do not top off or overfill
the tank and wait a few seconds after you have
finished pumping before removing the nozzle.
Clean fuel from painted surfaces as soon
as possible. See Washing Your Vehicle on
page 446.
When replacing the fuel cap, turn it clockwise until
it clicks. Make sure the cap is fully installed.
The diagnostic system can determine if the fuel
cap has been left off or improperly installed.
This would allow fuel to evaporate into the
atmosphere. See Malfunction Indicator Lamp on
page 196.