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Old 12-03-2008, 11:55 AM   #17 (permalink)
dichotomous
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Join Date: Nov 2008
Location: vermont
Posts: 142

CivySi - '03 honda civic SI
90 day: 31.99 mpg (US)
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Quote:
Originally Posted by Daox View Post
VGs do not keep airflow pasted to the roofline. Thats just not what they do. They will induce turbulence (which is bad) to slow the air down and allow it to follow a steeper curve. This, at the very best, increases the pressure on the rear window of a sedan which does help. But, the turbulence induced by the VGs normally offsets any gain.

I have never seen any documentation (from people not trying to sell VGs) that shows that VGs improve mileage. MetroMPG has also done testing that supports this.
well then, we shall see! ths being the point of putting them on there, I may take them off at some point, but they are behind where the airflow seperates so they should not add much in the way of drag, but they do seem to keep the air on the roof as explained by the dry roof, I'll see how they handle snow.
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