question about car models & double sided faces

[zimluura]

i read in the car development wiki that double sided faces aren't supported.
but i took it to mean, at first, that everything should be a solid mesh so triangles could be drawn single sided (cw, ccw). but when looking at another car (tc) i noticed that the mesh isn't solid and that triangles were being drawn double sided. basically that inside the engine bay, when you look up at the hood with freecam it's has the same texture as the top side of the hood.

so anyways, since i'm working on a car i sorta want to know how i should be piecing things together.

do i make the meshes have a zero volume kinda feel. like if you were to dunk them in liquid they wouldn't displace any of it since they're infinitely thin. this seems to work fine in the windows release from march. but how does the development version of the game handle this?

or

should i make each one have a solid construction (something that would displace water)

am i being clear with my question here?? thanks in advance.