Folding table that attaches to the headrest
I found a set for sale on Amazon and there was a disclaimer that it should not be used while the back seat is occupied.

https://configurator.mercedes-benz-a...nt_A0008160000




It get's good reviews, though seems rather expensive for what it is...
The disclaimer makes sense in a way: you wouldn't want to have the table in front
of you during an accident i guess.
The Amazon disclaimer piqued my interest yesterday and I looked on a couple different websites and couldn't find any such disclaimer from Mercedes. I think it was just that specific seller was adding his $0.02 to maybe avoid a lawsuit or something.
I thought the same as you did at first about having an accident with the table down. Then I thought about the executive interiors available on the S550/600 and both have tables that fold out. I'm 99% sure it was just that person trying to be extra careful. I kinda chuckled to myself a little bit trying to imagine a driver trying to turn around to grab the coffee sitting on the table in the back seat.
Usually not a problem, but I am tall so I occasionally have to move my seat to accommodate people in the back. The power headrests move themselves when you move the seat, and they don't like being restricted by the hanger clip.
Other than that, no problems at all, and it works great! I can imagine it would be just as useful with a table attached.


