i think this would be a perfect shape for a coupe-sedan type of car like merc's CLS and VW CC cars.
I like it actually, since it allows for new shape and if done right, it might be a great looking car. And fastbacks like this are hugely practical. Kinda nice for those who dont want touring, but think sedan is bit too limiting. on RWD car where boot space is taken up by all the mechanical bits in the back, this is good idea.