I've never noticed this on any car before.... Ever.

Today, while parking, music off, everything quiet, I was merely very slowly braking, then inching closer to the a curb stop (no Gas applied at all, just the "D" or "R" roll, and a brake), and I could hear the gas in the rear tank VERY MUCH "splashing" or "sloshing" around. Like it sounded like I had one of those huge office water cooler tanks in my trunk.

Actually, the best way to describe it, is imagine shaking around one of those water-cooler tanks, and that muted sound of large amounts of water splashing everywhere inside a confined area, is what I heard.

To note, I have about 3/4's of a Tank right (full) right now.

It was probably that beer you had just chugged down at lunch.

LOL. It sounded like I had a half full keg in my belly then, swishing around like it's nobody's business.

Is this a situation where you can take a car in for Warranty? Or just the nature of the beat I wonder.

Didn't realize you are one of the little people.

No size offense intended.

My c320 (while a much cheaper car) does the same thing.

2 questions: could it be the air compressor or air tank for the airmatic suspension? sometimes makes noices that could be construed as sloshing.

otherwise maybe you have a broken baffle or baffles in the fuel tank. Get it checked.

No it's definitely the fuel being very easy to hear. Now I'm thinking it could probably be heard from the outside if that's the case as well, perhaps. However again, I can only really notice it in a quiet area, with the music off or very low.

Thanks, yeah, I guess I'll tell them about it whenever I take it in.

BTW, what exactly is the fuel tank baffle?

Pieces of material put in tank with drain holes so gas will flow to fuel hole. Put in especially to avoid noise of which you speak.
Keeps fuel in little compartments so there is no noise and weight shifting around, holes are there to allow fuel to go to pump hole.

Hmm, interesting thanks. I'll definitely make a deal of it when I go in, as to get them to check it instead of doing the "they all do that" routine.

the only resistance you may get on this is generally if there is a broken baffle you sometimes get a clanking noise too as you basically have a piece of metal floating around in there. see if you can detect anything like that.