Yes, we have a keyfit 30 as well and when it's in the middle, both front seats in the X3 can go all the way back without a problem.
Originally Posted by ND40oz
I'd at least try it in the middle to see if it really doesn't fit, that's where we keep our chicco keyfit 30 and it has plenty of room to clear the seats in the X5. I don't remember the X3 being that much tighter in width that it would cause an issue, but you may just have a huge carseat.
2011 X3 (F25) xDrive 35i 3.0L, nav, xm