This panel will make a noticeable difference in the MPG, maybe 1 to 3 mpg. But I can easily see some people removing it and add an after market trim or other 'show' parts for cool factor, along with open fenders and wire wheels. For those people getting only 75mpg, they'll say 'so what!'Ekh --- Actually each side would need 7 holes for steering and suspension members to pass through the body work. Each of those holes would need to be elongated to allow for movement. Small rubber boots or sliding fairleads could make an effective seal. It would be a real PITA to work on but at least steering and suspension components normally don't need frequent maintenance. Though I do hope the ball joints and tierods have grease fittings. Most modern vehicle bearings are "lifetime" lubricated which of course means they're good until they wear out. Planned obsolescence.
And inevitably some one will 'donk it'. lol Autocycle with Donk link