Show me a real scientific study that shows airtabs have helped with fuel efficiency on anything. The studies done by air tabs themselves hold as much credibility as the studies on websites done by powerbands, LED light therapy, or water ionizers for health and HHO generators for fuel milage.
Here's some.
What is Water Ionization
- Light Relief
Power Balance - Performance Technology
Running Your Car On HHO Gas - Scam or Solution?
These sites use pseudoscientific babble to make you think that they are legit, when in fact they simply dazzle with bull s#!t in order to sell their junk. Kind of ironic that a device purported to help lower the suction on the back of a vehicle really is made for suckers.
Here's a website the eviscerates water ionizers.
"Ionized" and alkaline water: snake oil on tap
I acknowledge that the vortex generators may do some good in situations where the attached airflow is right at its limit on the back of the roof on a sedan, but these applications a very specific and the only credible paper I've seen was done by Mitsubishi.