Doing a bit of research on my new L494 and just noticed that the previous parking brake arrangement using the cable driven brake shoes inside the drum at the centre of the disk has been changed to a direct action, now driving the disc pads directly onto the disc. The park brake was always a potential issue on the D3, D4 and L320 RRS and it looks like they have made a major change.
Electric motors on each rear caliper now drive the disc pads directly onto the disc.
I didn't have a problem with my D3 or L320 park brake but I did maintain it regularly to avoid the "screaming" issues etc. Hopefully the new arrangement is more reliable.
Regards
Barry