A car seat fits behind the passenger side with no problem but it wouldn't work behind the driver seat when I'm driving but I'm 6'2". Our stroller fits behind the seats. I'm basing this on a 10 month old with the seat facing rearward.
1995 325i,1996 328ci,1997 528i,1997 Z3 2.8,
2001 X5 3.0,2001 330i Conv,2002 M3 Conv,
2003 M3 Coupe,2004 M3 Coupe,2004 Z4 3.0,
2004 X3 3.0,2007 X3 3.0,2007 335i Conv.,
2013 X1 28 sdrive M Sport, 2014 M235 on order