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Old 11-28-2007, 08:48 AM   #6 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

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

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
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Did a non-rigorous test - A-B only. (Cardboard/duct tape prototypes don't lend themselves to removal & reinstallation, so sorry, no A-B-A.)

That said, conditions were PERFECT. Next to no wind.

Results @ 55 mph (88.5 km/h)

- with partial boattail: 61.23 mpg (US) avg.
- without boattail: 59.85 mpg (US) avg.
- partial boattail gain: 1.38 mpg (US) / 2.3% above "stock"

Conditions:
Observed at: Grenadier Island 18 July 2006 4:00 PM EDT
Temperature 28°CPressure/ Tendency 101.5 kPa↑Humidity 63 %Humidex 36 Dewpoint 20°CWind calm DRLs, alternator ON, fan ON @ 3

W E

Partial boattail
59.8 61.6
60.2 63.3
59.4 63.1

61.23333333 avg

Non-boattail
57.2 61.7
58.7 61.8

59.85 avg.

Observations
This is about in line with what I predicted, based on the gains seen from grille block & wheel skirts (5.7% combined).

The difference between this mod and those, is this is a complex shape which can be optimised with tuft testing. The others were essentially no-brainer gap-fillers.
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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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