How are you exporting from Maya? I’ve ran into issues before with trying to export models with smooth preview as FBX. I found it was better to bake the smooth down in Maya first, then export.
Also exporting as USD has worked much better for me, as it is much much faster than exporting FBX for something like a CAD vehicle model.
If you do export as USD, make sure to set Subdivision Method to ‘None’, otherwise the file translation into Unreal will shatter normals, edges, etc.
When importing USD into Unreal, uncheck all options under ‘Kinds to collapse’ otherwise the model will be combined into one mesh/actor. Also set Nanite Triangle Threshold to a very high number like 100,000,000, otherwise Unreal will convert any mesh over that tri-count to a Nanite mesh, which I have found breaks the meshes entirely.