The three cigar lighters of W211 E320's normally go "dead" when the car is turned off. However, it is well documented (and true) that if you go to fuses 53 and 54 in the fuse compartment under the hood (driver's side, in US) near the firewall and move the two fuses to their alternate positions, you can make the front console cigar lighter always "live". The actual fuse you need to move is 54. I am not really sure what 53 does, but most folks move both.


This begs the question of what, if anything, this does to the rear seat cigar lighter and the trunk cigar lighter. I had hoped that at least the trunk one is on the same fuse as this would simplify connecting a battery tender for when you store your car. (I have been using the front console cigar lighter to keep my main battery charged in storage.)


Well, with the help of a volt meter I found out that, sadly only the front console cigar lighter is on the fuse 54 circuit. The other two cigar lighters are not and go dead when the engine is off no matter what you do. No joy.


Not sure why MB would wire things that way, seems dumb to me, but I am not a German engineer who loves to make things more complex than they need to be. I guess we should be grateful that you can at least make that one cigar lighter socket always "hot".


By the way, the cigar lighter socket in my E46 BMW is always "hot". You don't have to do anything. BMW engineers must be a bit different from MB engineers.