Cadillac 1996 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 is located
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).