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Old 07-13-2015, 12:05 PM   #93 (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 - '14 Mitsubishi Mirage ES (base)
90 day: 65.39 mpg (US)
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air dam 2.0 observations; MPG comparison

So, after a week of having the new air dam on the car and several drives under my belt, some observations:
  • I've scraped it on bumps & driveways maybe 3 or 4 times. That's much less than the one I had on the Civic (3.5 inches clearance vs. 5). Have you seen the OEM air dam height on the Chevy Volt? They must scrape a lot.
  • My Extremely Scientific and Accurate Butt-o-Meter says the car coasts further and my Non-Confirmation Bias Seeking Eye says the ScanGauge seems to be reporting better MPG at steady speed.
I was able to make a MPG comparison of a pre-air dam vs. post-air dam round trip...
  • 76.8 mpg US (no air dam) round trip (87 km / 54 miles)
  • 82.5 mpg US (air dam) same round trip
And that was with a 3.2 km/h (2 mph) higher average speed with the air dam on (low 30's avg mph; max of low 50's; cruising between 45-50). Similar weather & traffic conditions (mostly deserted country roads with more than a few stops & turns).

Big disclaimer: unfortunately I changed another major variable to confound these results because I also put RE92 low rolling resistance tires on the car in between the two trips.

I think I may do an A-B-A of this air dam though. It seems like it may show up above the normal noise of testing variability.
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