Rear window spoiler (non-hatch/wagon)
 

With all this talk about the Evo Vg's, I want to bring up something else; the ~06 Subaru WRX STI rear window spoiler.

Id assume that this is suuposed to work in the same fashion as the Evo VG's. My only question is, would it be better than the VG's in keeping the airflow attached to the car?

Or do you think that once the air starts to exit from under the spoiler, it wants to kick up away from the car increasing the amount of air hitting the trunk spoiler to increase the downforce?

I assume you're refering to the roof spoiler of the older generation STI, like this?

https://istargazer.ca/sti/cf_roof_van...f-spoiler6.jpg

If so, you're correct...its the obvious and more aggresive approach to what the VGs do for the EVO. The drawback is the STI deflector probably creates much more drag & lift than the EVO's VGs. But the lift is basically canceled out by the huge trunk-mounted rear wing.

yep, thats the one im talking about.

good post. i've been looking(admiring) at ones i see on the road. two questions:

are there aftermarket spoilers available, for...oh i dunno, a chevy prizm maybe?

and if so, is it worth the investment to help achieve better aero and ultimately save significant $$$?

without seeing one in a wind tunnel, like the evo engineers have done, i wouldnt want to spend the money to find out it created an even larger low pressure on the rear window. and then without a gigantor spoiler on the trunk to correct it, youll be up sh*ts creek with a huge wake like your driving a small suv.

i think vgs are still the so-so way to get rid of that little bit of drag off the rear window. ill be trying out vgs (when im dne with my underbody) as driving when it stops raining, i can see dry areas on the sides of the rear windows but still wet in an ovular area in the center of it.

IMO, those deflectors are not conducive to good fuel economy since drag & lift are not favorable aero characteristics. It only works for the STI because its built for performance, not economy. VGs are a more passive approach to achieving the same goal and are more widely accepted in the FE community because they don't generate nearly as much drag/lift.

SL8Brick