Cadillac 2004 Seville Owner's Manual page 268

To open the fuel door, press the fuel door release
button upward. The vehicle must be in PARK (P) or
NEUTRAL (N) and the valet lockout button must be
in OFF.
Pull the strap to release the fuel door.
5-8
An alternate fuel door
release strap is located
inside the trunk on
the driver's side of the
vehicle.
While refueling, hang the fuel cap by the tether from the
hook on the fuel door.
To remove the fuel cap, turn it slowly to the left
(counterclockwise). The fuel cap has a spring in it; if
you let go of the cap too soon, it will spring back to
the right.