Hi there. I am 188 cm tall and with very long legs
There is no problem for my wife, 167 cm to sit in the rear seat behind me, but there is not much space leftover... As for the front facing toddler car seat I really canīt tell. Maybe someone else on the forum can...
Take a look at the BMW web-site, there is an original seat called BMW Junior Seat II that fits for the X1.