Here is a radical Gen II Prius implementation that is way more than an
"aero crease:"
The little circles are clear plastic to allow the tail lights to be seen from the side.
If a modder was particularly clever, this could be roughly reproduced with a
slightly curved sheet of coroplast (with the holes) or clear plastic. I suppose
they are intended to act like a vertical version of a rear deck-edge spoiler.
This feels like a super short version of the Geo Metro boat tail without a "transom."
While we're at it, here are a few more views of drool-worthy details on this car:
Rear wheel shirts
Front wheel covers
From what I've been able to uncover, this car is a one-off and none of these
parts are available for purchase.
