Thanks for the comment. I agree that this is probably a burgeoning problem, now making itself known on the newer models.

And I did a search as you suggested using "vacuum pods AND air vent." It returned a lot of interesting results with very similar symptoms.

However doing a search for "W202 AND vacuum pod" gives zero results. Finding a step-by-step procedure to fix this problem on the W202 C230 / C280 / C36 would be great!

(I still have no idea if my slow trunk latch, as described at the top, is related or just a secondary problem.)