Ok, this brings up the whole body style issue, which is a big deal for me. I like to carry stuff in the back of my 3 series: in particular a bicycle.
BMW has a great design for folding rear seats on the sedan and coupe. The head rests are separate from the folding seatback so the seats fold nearly flat without having to remove the headrest. This makes the coupe, in particular, vastly more practical than it's competitors (esp the Infiniti G37 coupe).
But the folding rear seats are a rare option on the sedan. I buy used so I can't order this stuff, and I also demand a manual tranny.
My solution? The coupe. Oddly enough, the coupe ends up being a little more practical for me. It is a little longer. The folding rear seats are standard. The manual tranny is less rare. My bikes slip in the back fine. I even have a custom trunk liner that is expandable for when the rear seats are folded down.
If I were king? Make split folding seats standard on the sedan, and make the coupe trunk a hatchback if it could be done without changing the styling or compromising the structure.
The GT would seem to be aimed at someone like me, I love all the extra space and accessibility of the trunk. But damn, man, you are forced to look at it every time you walk up to it. It is the automotive equivalent of a 2 bagger.
I am perfectly happy with my 3 coupe SUV!