From Udo Lidner's press presentation:
Besides sportiness, the new 3 Series Coupe had to be an elegant car. That is why we balanced its styling between our design principles—short overhangs, a long hood and a set-back greenhouse. Long doors and very flat front and rear ends accentuate this.
To create elegant styling, the silhouette could not be wedge-shaped—you need harmonious tension from the hood to the roof.
The closer you approach the car you discover the bright and dark transitions and finally, you see the 3-dimensional shape.