Loud hatch lock
 

On my 2003, the hatch lock seemed very mechanical and clunky.
I took the entire lock assembly apart.
Inside is a spring, a helical cut sprocket and a few other nick nacks.

BMW used a very light grease for the assembly.
I regreased it with a heavier weight grease.
It did quiet it down considerably.

The 2004 has a soft close mechanism and its less noisy.