Several years ago, there was a research on 'wings' and most where found to be a et scrubber on most,
I don't remember the speed ex , but it was somewhere above the 120 mark before it started adding down force to the car until then it was a drag and took more hp to start over comming that effect.
All the big fuel guys have to have them in order to 'hook the car on the big end of the track, but , if you notice they get to play with the degree and height depend on type of track , and temp air density
so for the big boys it is a tunning device