[aerohead]

Originally Posted by serialk11r

No what I was trying to get at is you would have to do a lot of cutting into most cars to get flying buttresses, so I was wondering if the winglets alone do anything, or if just the piece perpendicular to the window that forms the root of the winglet would have a similar effect.

By 'winglets' are we talking about the roof extensions, extending along the roof contour, as would happen, had Lotus just put a 'Kamm'-type roofline?
Combined with the pop-up spoiler, air coming around the rear pillars is captured under the over-gang, where vortices might have formed.
The vortex pair would have created induced rear lift and drag.
The overhang and spoiler conspire to kill the lift and drag both.
By not doing a Kamm-back, the driver probably has better rear outward vision. Less blind spot.