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Old 09-18-2021, 09:41 PM   #23 (permalink)
Vman455
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Pope Pious the Prius - '13 Toyota Prius Two
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Quote:
Originally Posted by tomi_k View Post
So based on your pressure measurements as mods on your spoiler impacted to the rear window / area surface pressures, did that help on fuel economy? And if did how much?
That's impossible to give an exact number either way, even though you see so many people try to do that on the internet; there's too much variability in the real world and I don't have access to a laboratory or wind tunnel (and unfortunately, the Prius has an electronic throttle so I can't use throttle-stop testing to see if it might be reducing the overall drag). The only thing I can say is: I ran a statistical analysis of the 6 months of tank fills prior to fitting the spoiler and the 6 months after fitting it when I took a stats course last year, and there was significant evidence to conclude (with 95% confidence) that the mean fuel economy per tank was greater after the spoiler was installed. That suggests it is helping, but there's always a possibility it's something else.

Keep in mind that just because it appears to be helping my car does not guarantee it will help yours; you will have to test your design yourself and find out.
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