The back seat cushion comes out easily. There are a couple release buttons on the lower front edge of the cushion, where the upholstery meets the carpet.

Best if two people do this. Push in the button and lift the cushion bottom up on each side. Carefully ease the cushion out from under the upper cushion then maneuver it out the door.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech