The driver side dash has ample knee room and head room compared to 3-series vehicles. If you raise the front seat higher I've found you can have comfortable space for both the front and back seat passenger (especially with panoramic roof open.
Also, while my vehicle was delivered with the rear seats in a normal position, I discovered they could be reclined further. I rode in the backseat comfortably while I let my friend test drive yesterday.
Our car seat is installed on the passenger side and there is definitely less space vs the F30.