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Old 03-13-2009, 02:30 PM   #1 (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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Coastdown testing question: does starting speed matter for consistency?

A question for the physics-minded among us:

I'm wondering how important is the consistency of initial speed, A, in coastdown testing where the data gathering will begin at speed B, somewhere below A.

EG: let's say I decide to measure coastdown times/distances from 90 km/h to 0 km/h.

Does a vehicle decelerate at a different rate from, say 90 to 80 km/h depending on whether the initial speed (clutch in/neutral) is 95 km/h or 110 km/h?

Just wondering for the sake of producing the most reliable results.

And no, my cruise control is currently NOT working, which is really why I'm asking . Don't want to rely on wetware (me) to accurately control speed if I don't have to.

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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



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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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