Interestingly, Ford changed something in the 06 and 07 models to increase fuel mileage -- a lot of anecdotal information confirms that these two models years of the original body style do get better mileage than earlier examples.
From the factory, the crossbars were optional; they're very removable.
The rack itself isn't designed to be removed, per se -- but over on focusfanatics.com there are numerous threads about removing
the rack, more for aesthetic reasons than efficiency.
It can be done -- holes must be plugged, headliner messed with, etc.
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