Why would you own a Sedan that your friends can't fit in w/o their knees digging into the seat-back and their shoulders being ontop of each other? What if you were a passenger in a friends car on a ski trip? You would be annoyed the whole ride. Or they could have a car that can fit 3 adult males comfortably.
The current Impreza is a great size (ok, excessive head room).
Just about everday I used to drive my co-workers to lunch. 3 guys could comfortably fit back there.
My other co-worker had a 3 series. Good luck. 2 in the back, shoulder to shoulder. It is horrible shoving a third person inside.