PhysX allows only either spheres, cubes, capsules and convex things - custom shapes made of several, custom orientated, scaled and positioned shapes.

For a client, I needed very accurate physics shapes. So I took WED and created several scaled boxes, imported them, positioned, rotated and scaled them, to match the needed shape:



Then, I wrote a small Lite-C script, that took the arrangement and wrote a MDL file, that encoded the position, scale, rotation and type of each sub-shape. During runtime, I load the MDL, read out the data and use pXent_addshape to build my custom and yet accurate complex physics shape.

Yes, and it involves work. But in an ideal work, your modeller creates the model for your vehicle once and therefore you need only once to create such a setup.