Pixyz Studio convex decomposition (Colliders for Physics)

We are trying to use the convex decomposition function of Pixyz Studio to create colliders for physics.

We can get satisfying results for geometries that are split up into several smaller parts.
However for our main use case that is to create colliders for a large mesh (car body) the results are very unsatisfying. The created colliders have a very low resolution, are blocky and do not match the form of the car body. That is independent of the parameters we pass to the function.

Has someone experience with creating convex colliders for larger meshes and can give us some advice?