Here's another cap from that shot.
This is at the very beginning when its the furthest from the camera. I feel like this is the most telling of the fact its new/CG simply because the shape IS perfect to a schematic. In my experience, the things that make CG look real are imperfections. Warping the mesh a little
bit may help sell the look.
I'm sure the mesh is accurate, I don't think it's that. It's the lighting, particularly on the secondary hull. It's just too bright.
Bathe it in harsher shadows and add a bit of film grain and it'd probably look alright. The CGI shot of the saucer separation looks absolutely fine - again, harsher shadows help. (Or that may have been a matte rather than CG, I couldn't tell.)
Cheers, saved me the bother!