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Old 05-22-2008, 10:24 AM   #9 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,527

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 62.14 mpg (US)
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Quote:
Originally Posted by JohnnyGrey View Post
Forget the scangauge. It lacks the accuracy and the resolution to tell you anything meaningful.
That's not my experience using one in controlled conditions. The last series of back-to-back runs I did testing vortex generators had a standard deviation of .6%. I'd call that decent resolution. It's less important that the absolute MPG readings are 100% accurate, as long as the relative differences are consistent.

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However, I would say that tank-to-tank "testing" of acetone is a waste of time. Too many variables involved to draw a conclusion. Despite the ambition, and the title of this thread, you're not going to "get to the bottom of this" on the road.

EDIT: the "idle" method you describe with a graduated cylinder would be more reliable. Don't forget you need to account for fuel return as well (if your van has a fuel return line).
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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
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