The Australian AutoSpeed web site recently ran a 4-part series on VG's. Some of the articles are open access, some require payment:
http://www.autospeed.com/cms/search/...vortex&x=0&y=0
The writers have done quite a few excellent articles on DIY aero mods before, and they're normally pretty rational and scientific in their approach (ie. decent methodology, healthy skepticism). I've paid the $5 to access a few of their articles in the past, and haven't been disappointed.
They claimed they "tested" VGs on the rear of an Insight and a 1st generation Prius in the last instalment of the 4-part series, so I bought access to one of the articles to read the results.
Save your money: there were no "results" because they didn't properly test them!
They did show a beneficial improvement in airflow down the rear window of the Prius via photographs of tuft tests, but they didn't quantify the results re fuel consumption changes.
For the Insight, they didn't even attempt to do controlled back-to-back testing - they just drove their regular commute over several weeks and then compared the results there to (apparently) a single commute with the VGs attached. That methodology sucks!
And it doubly sucks because this is the application I'm most interested in: ie do VG's have the ability to reduce wake / base pressure beyond the trailing edge of a hatchback-style vehicle?
Still, they somehow feel confident enough to conclude that:
Quote:
Quote:
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On the basis of the scientific evidence that is available, and the results of this test, we very much doubt whether vortex generators fitted to the trailing edges of vehicles will reduce drag.
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(emphasis added.)