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Old 04-13-2009, 05:17 PM   #5 (permalink)
Allch Chcar
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Join Date: Jan 2008
Location: North Coast, California
Posts: 429

Cordelia - '15 Mazda Mazda3 i Sport
90 day: 37.83 mpg (US)
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Getting poor shapes to flow better is the goal of our aerodynamics. What you start with doesn't matter as much as what you end up with.

The dirt building up on the back is a common problem with hatchbacks, minivans, basically vehicles that only "appear" more aerodynamic than the xB. The problem comes from the wake of the underbelly as shown in this topic about an European Swift. They've already discussed the back-middle spoiler keeping the dirty undertray air from building up deposits on the rear window.

The Metro has a CoEf of .36 and the '94 Mustangs have a CoEf of .34. A boat tail is ideal for the most slip but "boat tailing" the rear quarter can still give good results. If your only response is to buy a new vehicle or move within walking distance, you're not contributing anything useful.
-Allch Chcar

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