Quote:
Originally Posted by tomi_k
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?
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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.