The drag issue is key issue.  If there is more drag you need more energy to 
overcome it.  I would like to see the smoke test they ran.


----- Original Message ----- 
From: "Nate Duehr" <nate@natetech.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Wednesday, June 27, 2007 7:17 PM
Subject: Re: [EE] Simple fuel-saver, so they say


> Rich wrote:
>> I drive with the tailgate down when I use the pickup unloaded.  It does 
>> save
>> fuel because up, it can scoop up enough air pressure at 50 mph to cause
>> significant drag.   I have seen some kind of rubber or polymer sheet on 
>> some
>> pickups with big holes in the sheet stretched across the back, and no
>> tailgate.  I assume it is intended to reduce drag but at higher speeds it
>> seems that perhaps some significant drag may develop to obviate the 
>> purpose.
>
> This is exactly what MythBusters disproved.
>
> Having the tailgate up creates a vortex behind the cab to the rear of
> the vehicle and actually creates LESS drag when the air flowing over it
> of the main airstream interacts with the vortex instead of dragging
> along the bed of the vehicle.  A "buffer zone" of circular air motion,
> so to speak.
>
> The various "remove the tailgate" or "leave it down" products are snake
> oil. Those netting-across-the-back products were proven in the show (as
> was leaving the tailgate down) to have LOWER gas mileage than leaving it 
> up.
>
> Do your own tests (as they recommended) scientifically if you don't
> believe them, but they did a pretty good job of making the tests fair,
> and tailgate up won all categories.
>
> Nate
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