Matt, the fasteners that you refer to, are called "Dzus" fasteners (usually), or also "quarter-turn" fasteners. I like them too, as they make the removal of panels from a vehicle SOOOO much easier, and servicing a vehicle equipped in this way makes having those #$@%&***^$$## panels to contend with, not so much of a chore. The original purpose of the undercar panel was indeed, aerodynamics. Skidplates, as often installed on Dakotas, Durangos, GM S-10s, and others, are another important class of undercar panel. Sometimes, a panel can serve both purposes, and then it is heavy, in addition to being awkward to maneuver. REALLY fun when you are trying to re-install one of these panels on your back, balancing the panel in one hand. The manufacturers usually try to make the bigger and heavier panels easier to deal with, by having slots for some hardware, or the miraculous, 1/4-turn fasteners. BMW and MB do not seem to be on board with this, and I also question the wisdom of VW/Audi's use of plastic panels under their autos. These things can be huge! And the fastener count is always through the roof. My experience has been that every car with a panel underneath, is missing at least a third of its mounting hardware by the time I get to see it.