2004 Cadillac DeVille Owner's Manual - Page 288

The fuel door release button is located to the left of the steering wheel next to the exterior lamp control. The button only works when the vehicle is in PARK (P) or NEUTRAL (N), when the key is in the ignition and the VALET lockout button is in OFF. An alternate fuel door release is located inside of the trunk on the driver's side. Pull it to release the fuel door. While refueling, hang the fuel cap by the tether from the hook on the filler door. To remove the fuel cap, turn it slowly to the left (counterclockwise). The fuel cap has spring in it; if you let go of the cap too soon, it will spring back to the right. 5-8