Congrats on the new baby girl...I switched from a 2011 335(tuned) to a 2011 X5 50i with a mild tune and if power is what your after, I would say go for a 50i...For such a heavy truck I was very surprised how fast it is...It kept that ear to ear smile on my face every time I get on it compared to my 335...I've driven an X5 35i and the X5 4.8, they're very similar in power and you wont be disappointed whichever direction you decide to go...Any X5 you get will have more then enough room for your daughters baby seat...I recommend mounting it in the middle of the rear seat so both front passengers will have plenty of room to ride comfortably...Just don't make the same mistake I made and look past the X5M...I'm still kicking myself in the ass that I didn't get that instead
