Usually you can buy a 3d model
of generically similar to your car, or find it for free on the various repositories.
https://duckduckgo.com/?q=3d+capture...deos&ia=videos
3D capture is free on a smart phone. This generates a triangulated point cloud. The re-topo reduces the number of faces by orders of magnitude and reorders to quads. This reduces the task calculating the physics.