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Old 04-22-2020, 10:59 AM   #18 (permalink)
aerohead
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busted

Quote:
Originally Posted by COcyclist View Post



At least on the VW Golf


https://imgur.com/gallery/7sVGG7k


I have tried various forms of wheel covers for over 10 years on my diesel Golf 5 speed manual with no real improvement in highly mpg. I have had several entire tanks testing them where the mpg seems to go down. Wheel covers are one of the first mods many people try on this forum. There is a historical tradition of using Moon wheel covers on salt flats and intuitively they “look” like they would work much better than the blender blade mess of most alloy rims. I recently purchased Julian Edgar’s book and he quotes several studies of airflow and drag on car wheels. These studies show that totally smooth wheel covers are not the lowest drag option in modern automobiles. This would fit with my personal experience and motivated me to do some further testing in an A-B-A or even A-B-A-C-D options. I will post my test data and observations in a following post.
How does that conclusion square with counterfactual evidence achieved from direct wind tunnel measurement? Why is Julian authorized to overturn nearly a century of observations and measurements?
How many,out of the total population of 'modern' cars are represented in these remarkable findings?
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