noticed i said PARKED! but its a chevette, there is no seal...

That's really cool.... That would be nature's attempt to fix what's wrong with the design ;) Trying to get closer to that natural teardrop shape. It also shows the importance of the rear end (meaning - downstream features) with respect to aerodynamics.

If you wanted to find the ideal shape nature intended (if nature intended cars :P), build up some light and fluffy snow - enough to cause trouble with flow. Then hit the highway and let the snow blow off.... Of course, that won't work beyond the bumper very far :P

Again, that's really cool - I don't live an a region that snows so I never get to see anything like this on my vehicle :P

actually there is a seal, or at least there should be.