UV Overlapping on CAD Models, questions on lighting for CAD


I have questions regarding a project I am developing using a CAD file for a car. I have tried using both iges and step files exported from fusion 360 and I am having issues with overlapping UV errors when I build my lighting.

I have seen a number of tutorials on lightmapping in Blender and other programs but I see no options for CAD models (since CAD has no light data) can someone please point me in the right direction of tutorials on CAD model lighting.