Someone said wings were not effective at speeds below 150 mph.
I occasionally race in SCCA Formula Continental class. These are essentially Forula Fords with 2-liter engines and wings front and rear. I towed my car on an open trailer. I was alwys surprised at how much harder it was to pull an
1100-lb car, when I hardly noticed the trailer when empty. In fact, the trailer felt as heavy with the little formula car on it as it did when I towed a Pinto or other small sedan at twice the weight. I could hardly get to 70 mph, even using a van which is slightly more aerodynamic with a trailer. Then one trip I got about 5 miles from the house, on the freeway, bucking a headwind. I pulled off, removed the rear wing and tossed it into the truck. Without that wing in the airstream, it was like towing an empty trailer again. As much drag (and downforce) as it created at 70 mph, the effect at higher speeds must be considerable.
Granted, on the typical rice-rocket that airfoil is probably shrouded in the airstream and likely angled wrong, but it has an effect in all but the most unlikely orientations.
YMMV