HI
i am trying to make a car crash using cloth. simulation takes something like 12 minutes per frame even though mesh is not dense at all. i thought may be i use some wrong approach?

i guess problem is in self penetrating edges. if that the case what is a work process?

Your file was kinda broken when I opened, for some reason it was missing the car, so I re-imported it.
Yes, the mesh is not dense. I'd still rather shrink-wrap a simpler, more uniform mesh around it. If you look in the cloth masterclass, the proxy geo that was created to sim a car crash was a single piece of geo, nicely divided, with not as many kinks as the actual car geo. That might help you a lot.
Once the sim is done, you can use cloth capture and cloth deform nodes to transfer the deformation to the actual car mesh.
Also you had minimum substeps set to 32! That sounds unnecessary, set it back to 1 and reduce the substep tolerance. The solver will adaptively increase the substeps as needed and the lower the tolerance, the more substeps it creates until it reaches the limit.

Cheers

Thank you very much for reply. It helped. But may be you know how should i include interior or doors into a simulation if it supposed to be a single mesh?
p.s. i am sorry file was not corrupted, i just don't know how to save a scene with imported file.