Either in brine conditions or in drizzling conditions where it hasn't rained hard enough to wash off the roads, the headlights can get filthy. The headlight cleaners do help.
I would ask for the contact for the 300E Euro lights, but the poor fellow has worn out his keyboard, sending it out to everyone, I'm embarrassed to ask.
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in