[FrankP]

Is there a drop-in unit for the late W140 cars that
plays multiple MP3-encoded CDs?

It is easy to find straight-CD multi-changer, but
I run out of music before it is time to fill the
gas tank.

What we need is about 2 gas tanks worth of music:
about 10 hours. Are there any drop-in units that
can do it without requiring ripping open the dash?

 

[foleydb]

This may be what you are looking for:

http://www.alpine1.com/html/D2_n_1_n_n.html
...

This may be what you are looking for:

http://www.alpine1.com/html/D2_n_1_n_n.html