[doviatt]

Airtabs or vortex generators were not designed or intended to reduce drag or increase forward efficiency in any way (originally). I would guess the origination of this claim of efficiency came from the product web site for cars. We all should know they originally appeared on airplane wings to help keep airflow from separating from the wing for the purpose of lift. This being in a vertical direction. It only takes someone with a marketing mind, sitting on an airplane, looking out the windows, noticing those tabs, thinking "I wonder what those are for". Then his marketing mind starts to engage and his motive is "I can sell these, they look cool. What can I use as the selling point?" Since cars do not benefit from improved vertical lift near the stall speed at critical angle of attack...;-)
...make up something....

They just add more drag. Period. Even on those airplane wings they add more drag. The trade off is better near stall performance at low (landing speeds) with attached airflow. They have no benefit at higher cruise speed. Just more drag.

I'm glad the testing is being done though. All ideas should be tested.