Unofficialbmw.com

[t white]

Remove the rear seat squab (the bit your rear sit on!) by either pulling up sharply the front edge or on some models there was two screws holding it down just below the font edge. check for the screws first obviously. The back cushion (the bit your back rests on) is held in by two self tapping bolts (8mm I believe) in the lower corners where the rear side panels come to an end (ours was a 2 door but the 4 is the same. These fixings are always hidden behind flaps of trim. peel these back to remove the fixings. once out you pull the bottom of the seat forward and lift it straight up. the top of the seat hooks over the lip of the rear shelf.

Hope this helps

Trevor White '93 525isea Surrey U.K.