Call me crazy, but I still think no differential, drive train, suspension components,
&c. would be somehow preferable to a picture of them pasted onto a mirror-smooth surface.

It tells me that it's a work-in-progress; that the developers are waiting till they can do it right to do it at all. Otherwise it just looks like a shoddy finished product. I'm the type of guy who lives in an unfurnished home till he can afford exactly what he wants, as opposed to using temporary furniture. I suppose you would say I don't like
substitutes.
Anyway, parts of the differential, axles and rear suspension of a lot of cars can be visible from behind (without flipping the car over) and a texture wouldn't help in this regard.