Originally posted by RichardM
Its in the owners manual for the E class, that you move a switch behind the lights.
Click Here to read the on-line manual then select 'Driving Abroad' to open the PDF file
According to the manual there is a switch on the back of the lights to switch the headlights to symmetrical dipped beam (rather than asymmetrical).
There is a warning at the bottom saying to always have work on xenon headlamps carried out at a qualified workshop but it doesn't make it clear whether you can switch them yourself.