BMW changed the central locking system's "double-lock" feature starting around the 2000 model year (sorry, don't have a build date).
All of us old timers that are familiar with the double-lock feature actually meaning that the interior door handles NOT being able to be opened...well, BMW changed this to where someone locked inside the vehicle (intentionally or unintentionally) can now get out of the car.
From 2000 model year-up...if you've been double-locked inside the vehicle (or outside the vehicle)...if you press the central locking button on the console first, then pull twice on a door handle...the door will now open...BUT...the alarm will sound-off, too. Prior to the 2000 model year...if you were double-locked inside the car...you'd remain there until you broke a window to get out, or someone arrived back at the car with a key.
But the above means nothing if the vehicle's battery is dead and the doors are double locked. A way to manually unlock the door is required, or a way to get some power to the vehicle is needed...or some other resourcefulness.
