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Old 12-16-2007, 02:47 PM   #6 (permalink)
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
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It is only logical that a better flowing filter make better MPG.
The most significant flow restriction in a gasoline engine is the throttle plate, not the air filter. The only time I'd grant that an air filter will aid fuel efficiency is when the engine is operating at WOT, and the effective restriction shifts upstream from the throttle plate to the filter and possibly the intake tract.

But since we don't drive around at WOT, it's a moot point.

I also stick by the marketing argument: if K&N believed their filters boosted fuel efficiency, they would be marketing the crap out of that angle.

But they don't, because the know they can't prove there is any significant difference. So instead, they dance with customer testimonials, knowing full well that the majority of their customers don't have the inclination or ability to empirically determine the filters' effects on fuel efficiency.
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown

has launched a forum for the efficient new Mitsubishi Mirage - fuel efficiency info for Geo Metro owners - electric car conversion on a beer budget
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