Xringer -
Interesting. When I look at the EV1, I notice the side of the car "curve under" the car. I think that extending the wheel skirt down would have required them to bulge it out, which would have increased their frontal area.
I want to do something similar, partially for my own aesthetic reasons. Here's a mock-up :
I put an angle on it because that angle matches the bottom rear horizontal of the bumper.
CarloSW2