I've owned a couple of Mercs - all E class - one saloon and a station - the electrics are NOT failsafe - and in fact I left the brand and went to Saab because I was fed up of constant electrical failures either from the lights, a/c, radio, or as on the worst occassion a complete failure of the main control panel which closed everything down including the assisted steering and brakes !
With the Saab, I've been completely trouble free for the last 36 months Whoaaa.