1996 Cadillac Eldorado Owner's Manual - Page 264

The fuel door release is located on the optional full console and on the Keyless Entry transmitter. If your vehicle is not equipped with the full console, then you must use the transmitter to open the fuel door. An alternate fuel door release islocated inside of the trunk on the left hand side. Pull it to release the fuel door. Hang the cap inside the fuel door while refueling. To take off the cap, turn it slowly to the left (counterclockwise).