"Matt loves his daily driver 2013 Chevrolet Volt, and in his original review, the only complaint was extremely loud wind buffeting with the windows lowered. Chevrolet has a fix for that, and Matt had it installed, so does it work? YES!"
This video shows (with audio) the before and after of the Chevy Volt's wind buffeting fix.
The wind buffeting that plagues the Volt can be remedied with an optional (free) fix, but it will impact efficiency, even if only ever-so slightly.
So, it's up to you to decide if quiet is worth the decrease in efficiency. The fix does work, as is clearly evident in the video above, but if the noise never bothered you, then perhaps eliminating it just isn't something you're interested in sacrificing some efficiency for.