AJI -
The Flow Illustrator is a tricky animal. The thread on it is a monster to read.
Flow from under the car will always be bad. My interpretation is that the curving downslope is too much, aka like a VW Beetle. I think it needs to be extended like so :
I say this because I think I am seeing a "virtual kamm-back" (or boat tail?!?!?) forming in the swirls. Notice that this makes it look like the new Prius and Insight. More interior volume too!
Articles I have read state that the Zoe does deploy a spoiler at highway speeds (just like the new VW Beetle), so maybe they are accounting for what I think is needed.
CarloSW2