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Old 02-23-2014, 10:27 AM   #5 (permalink)
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,461

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

MPGiata - '90 Mazda Miata
90 day: 55.97 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: 67.41 mpg (US)
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The thing is, I'm not convinced the popular teardrop builds & plans you see all over the web are all that aerodynamic. They only fit the popular stereotype of what "should be" aerodynamic based on their appearance to the uninformed. At the rear of the ones I've seen, there's far too much curvature -- like a VW Bug, excessive curvature at the rear = terrible drag.

They may not be any better than pulling a box of similar height. Even if they're marginally better, they're faaaaaar from optimal. They sure are cute, though.

If you're going to do it from scratch, I would design something that is perhaps a "semi-pop top", so that the height is close to (no more than) the height of the van at the front, tapering down toward the rear respecting maximum taper/curvature to preserve attached flow.

You could have a roof/upper section which is hinged at the front end and opens to give you standing headroom through the middle/back: think "clam shell" rather than
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

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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