Hi Chris,
First. WOW.... you are great to see those "shark gills"! I thought it was just wrinkles from a first attempt at a vinyl top. That my help narrow the time of the wind tunnel and dust resilience test videos. (Sorry I ran out of "likes" for today but "LIKE" to you!!!!)
Here is where I stumbled across the early testing video. The later part shows the neat stuff:
https://global.nissannews.com/ja-JP/videos/video-e3f77bf0445dce99ca6040492d01a69c-240z_s30_heritage
Some of the pictures above are from frame captures and tweaking of resolution and lighting to bring out points of interest
I dug a bit more and found a few shots here:
https://translate.googleusercontent.com/translate_c?depth=1&rurl=translate.google.ca&sl=ja&sp=nmt4&tl=en&u=https://nissangallery.jp/ghq/mikoukai_201401/&xid=17259,15700021,15700186,15700190,15700256,15700259,15700262,15700265,15700271,15700283&usg=ALkJrhif64yf2GBxy6LKqyizt2dI9P0rSQ
I believe the first Shark Gill car above is a plastic static model however the wind tunnel car seems like the one driven by Mr. Takei in the video.
The drip rail also curves in the wind tunnel car!
4 Gill
3 Gill with curved drip rail, and very early spoiler design