Mine similar piece from my 400, flew off on the highway. Luckily I heard it. Drove a bit till I realized and ran back to pickup.
So ordered more white plastic clips and epoxy glued them on the tabs of the tupperware while I used fiberglass strands and mat to fix the crack from a car running it over. No way in heck is it causing such a (noticeablr) degrade in performance/mpg/wind noise.
Why did the Cypresian cross the road ?
To get a little piece of tail .....with a crack in it :devil