In the article, there's mention of relieving air pressure in the fender wells. Some models have "brake cooling" tendencies with flow into the well, but I wonder if letting air flow out the rear of the area would provide a better overall flow of the vehicle?
Salt/Sand and grime may be harsh on the body or frame, but I'm thinking about how a notch or hole in the often-plastic shield behind the tire would help with improving air-flow. Maybe something that runs the air out and perhaps down under the car. That is, unless you have the area covered
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Maybe the front wheel wells could benefit most...
RH77
EDIT: Excellent article, BTW (as I read it again)...