If the Mercedes German engineering is anything like my BMW, the 115v adapter will draw power even when the vehicle is off...I came back to the adapter hissing and sparking and HOT.

I agree, but the cigarette lighter package is not 115V I believe. It is just a 12V, right below the radio.

Based on what I read, the rear passenger one, behind the center console(under rear a/c) is 115V(if we have the package) and I'm not even using it.

I can experiment with the front cigarette lighter one today and post the results.

No, that's not what I am saying...
I was referring to the 115v adapter you posted the link to above.
If you plug that into the 12v cigarette lighter, then it will draw power and hiss and get really got and possibly overload...does that make sense now?

Oh, I thought it won't overload, as it was designed for the cars to draw from 12V socket, to charge bigger appliances, as per comment section, which is popular 'breast feeding pump', Laptop or iPad, to blow air mattress(camping time) etc.

I do not think it will overload... ive used one of those a
"Converters" back in the day on my bimmer and it worked fine to charge my laptop. Havent tested it on my benz , but i do think , that u should be fine if you use a converter.

I just actually checked that Amazon link that you have posted earlier... and i did have something similar before , so just buy it and be happy. A pretty useful thing on long trips... esp. If you have kids.

I found th4 12V in the trunk


Also, just saw it on the cap of the middle outlet(back seat passenger) and it is marked as 12V.

trunk has one

way to go resurrecting a 5 year dead thread for your first post...lol

especially seeing the last post has a picture of and statement about the socket in the trunk.

Oh yeah, Welcome to MBWorld!

my 2016 wagon has one at the ashtray, one on the back of the center console, and another in the trunk area too.

if I was wiring something like a dash cam that was going to be semi-permanent, I would likely pull out the glovebox, find some useable 12V behind it and wire in a 'cigar' outlet with its own fuse (or maybe parallel it with the ash tray cigar outlet wiring), then tuck all this in behind the glovebox.

something like this,
since the plug is inaccessible, I would wrap it in tape, or maybe a couple tiewraps so it doesn't vibrate loose with age.

or, drill a hole in the glovebox (after verifying clearance behind it) and mount something like this so your widget is plugged inside the glovebox.
(same deal, wire it in parallel to the cigar outlet in the center console, or find 12V aux power somewhere handy)