It looks like the people who designed it looked at all the past studies into car airodynamics and decided they were all BS and then made it like a picture one of their 3 year old sons drew.
The guy at the car yard said alot of asians are really into them.
I caught sight of one the other day -- the asymmetry alone makes it a real head-turner! I like outtathebox thinking, and it''s made for some very successful marques in the past (PT Cruiser, Scion XB, and my personal favorite... the new MINI). If the Cube has functionality to go with its unusual looks... why not!
BTW OAAHR -- I thought Scion did a really nice job with their second-generation XB. I only got a quick glance at the Cube, but until I caught a glimpse of that rear window, I took it to be a newer XB...