Hm, something just occurred to me about that concept. I don't think the air intake above and forward of the rear wheels can be right.
If you look at the lines of the body, the air flowing in there is going to be flowing slightly upward due to the angles in the front half of the car. Since that line of flow, once inside the ductwork, has to stop at least before the rear deck, that means the air's upward motion has to be stopped by the upper portion of the duct inside. At speed, that would provide an upforce right over the rear wheels, exactly the opposite of what you want. You always want air to push you down, not up (duh). Yes, the air had to provide downforce as it angled up toward the intakes, but that force was only applied to the front of the car.
That can't be right. Either the orientation of the vents is wrong or my understanding of aerodynamics is wrong.
EDIT: Or the upforce is not significant enough to outweigh whatever reason put the vents there, I guess.