OK, pardon the poor image quality - because these are screen caps from some poor quality video.
Road speed is 70 km/h (43.5 mph)
Top = no vg's; bottom = vg's @ trailing edge of roof.
It's hard to see in the top pic, but the closest, middle three light colour tufts were swirling randomly, standing up at times.
FYI, the airtabs were duct taped to the roof of the car to facilitate installation/removal. The tape is flush on the roof & Airtab surfaces (the boundary layer here is significantly thicker than the tape anyway, so it would not affect the results).
Eight were installed (yes, one is black, the others are all white).
In this pic, the car is going about 50 km/h (30 mph).
Bad photography on the upper image. But you can even see the light coloured tuft on the right side of the center mounted brake light is standing up off the trunk lid.