I find it to be very difficult to believe that AirTabs & Vortex Generators do any good, except in very specific applications.
The reasons are these:
• If they create more thrust than the drag they produce, this would violate the laws of physics.
• The air being affected around a vehicle extends out several feet, it isn't all just within 1" of the skin. VG's seldom protrude more than 3/4" so the volume of air they have an effect on is very small compared to the huge volume that is in play, so it's doubtful that they could dramatically change the Cd.
• If they had measurable gains in fuel efficiency, we'd see them on production vehicles, you can't tell me that a cheap fix of adding these to a car or integrating them with the design of a car wouldn't be used if it could demonstrate 2-3 MPG's of difference. Car companies spend millions trying to figure out how to eek out that kind of FE gain.
• There is only 1 test I have ever see where they helped out a Mitsubishi Lancer, this took a team of engineers, a wind tunnel, and very specific placement to achieve a tiny gain in Cd. It is far beyond the reach of most people to figure out where & how to place these devices, and 95% of the vehicles made would receive no benefit from them no matter what number, where, or how they were applied anyway.
Show real reports by people other than the makers of these gimmicks showing an improvement in FE if you want to claim they work. My studied intuition says they're crap, they aren't in wide spread use commercially, and plenty of people have shown real results demonstrating they do nothing to help FE.
It is up to you to prove they do work, not up to those who are very skeptical to prove they don't. Show us real data, not hyped up marketing from someone who stands to make bucks selling these.