The back seat of a 5 series is in no way similar to the X, other than it being a back seat...it would be easier to have a custom rear seat made...

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1984 318i/man./Tornadorot*
1990 525i/man./Alpinweiß*
2001 525i/man./SP/PP/Cosmosschwarz/Sandbeige*
2002 X5 3.0i/man./SP/PP/Sirius/BT/Titansilber/Sandbeige*
2006 330i/man./SP/PP/CWP/Sirius/Blackline/Rear Fogs/Arktis/Grau*
2001 525i/step./SP/PP/CP/CWP/Xenons/Rear Shade/OEM Sirius/OEM BT/OEM AUX/M5 Rear Sway/Bilstein HDs/Beisan Vanos/Rear Fogs/Schiefergrün/Sandbeige*
2012 VW Golf R/Rising Blue*
2013 X1 xDrive35i Alpinweiß/Schwarz/M Sport/Premium/Tech
*retired