[ecomodded]

I have seen the tuft testing videos on youtube, People are video taping either attached flow or lack of flow over the rear glass with the vortex generators.
I do see your point of the different characteristics between a wing and a car. The wing needs lift to fly, the car needs lift to fly but its not good in the cars case ! obviously, So the place to use them on a car without generating lift is near the rear where there is no space to generate lift but space to direct airflow,which the VG's do. But alas, if the effect will have any outcome on fuel mileage is undetermined,i assume it would be minuscule at best. I do believe/ buy that they will effect or enhance the flow over a spoiler behind them.