Rear window and Airtabs (vortex generators)

[XJguy]

Independent test: Positive results.

Autospeed

[Joenavy85]

just proves the concept, no measurable effect on FE

[MetroMPG]

Hi XJguy

Here's another demonstration that Airtab style VG's clearly alter airflow over the rear window of a Toyota Corolla sedan. However they did not measurably improve fuel economy in A-B-A testing (on that car):

See: Tested: vortex generators (AirTabs) on a Toyota Corolla

The VG's consume energy (gasoline) to generate their vortices (this was evident to me in the subjective increase in wind noise I noticed in testing) .

So if the application in which they're used isn't ideal (ie. the VG's cause flow to re-attach on the trailing edge of a decklid where it otherwise wouldn't) then they may be of questionable value for fuel economy.

The Corolla decklid was apparently long & high enough, and this combined with the shape of the trailing edge of the roof, meant that the VG's didn't help compared to stock.