2003 VW Jetta TDI Rear Window Tuft Testing - Vortex Generators

[woodrobin]

Definite improvement. Bought a set for my Jetta based partly on watching this video.

[masterkdrifter]

what does this do?

[woodrobin]

@masterkdrifter It helps keep the layer of air moving along the contour of the car longer. The sooner it breaks away, the larger the area of turbulent, lower-pressure air behind the car. The larger the low-pressure area, the more drag, essentially trying to suck the car back into the low-pressure area (nature abhors a vacuum).