Trunk Release

The remote trunk release button is on the driver door, inside the storage compartment under the armrest.
Vehicles with an automatic transmission, the shift lever must be in P (Park) or N (Neutral).
Vehicles with a manual transmission, the shift lever must be in Neutral, and the parking brake set .
The trunk may be opened by pressing the remote trunk release button on the driver door, or
on the Remote Keyless Entry (RKE) transmitter, or the trunk release button located on the rear of the trunk above the license plate.
Vehicles with the Keyless Access System, if the vehicle is locked, the keyless access transmitter must be within 1m (3 ft) of the trunk for it to be recognized, then the trunk can be opened by the trunk release button located above the license plate. See Trunk (Sedan, Coupe) for more information.
Test yourself
A quick Cadillac CTS quiz: every answer comes with an explanation and a link to the manual page.