I just had to replace the lensunit on my passenger side headlight (1995 E420). The metal panel below the lens unit had no rubber trim on it at all.

Now, on my E420, the air intakes (2) are below each headlight (actually pulls air fron the grill area). I'm guessing that MB saw no reason to seal an area that was supposed to be ingesting air. However, the intake for your 300E may be in a different place.

Troy
1995 E420 79k