One problem related to headlights has been reported for the 2007 Mercedes Benz E320. The most recently reported issues are listed below.
Bought car new and love it. But last week the right low beam headlight failed. I had left and right h7 standard low beam halogen bulbs changed since the front bumper has to be removed. Later that day the new left side h7 failed. So my mechanic explained that the hella light fixture seen in mb, BMW, etc. . Commonly have premature disintegration of wiring insulation. They pulled both light fixtures, showing me the bare wires inside both fixtures. The mb wiring harness was unaffected. For the cost of about $1200 I replaced both hella headlight fixtures. I reviewed BMW and mb forums online and in both there are similar discussions about hella wire insulation failure in headlights. This is a dangerous and expensive issue. From the forums it seems that fires have occurred. It is possible that auto accidents have happened when night lighting has failed. At a minimum there have been many expensive repairs that should be part of a recall. I did not contact Mercedes Benz because this seems to be a global problem with a automotive parts supplier and not specific to mb or the e class.