I have tried the suggestions in https://www.beamng.com/threads/smoothing-groups-how-to-fix-them-for-everyone.9597/, however - I have been unsuccessful in getting a smooth mesh result in BeamNG. You can see it during my testing here: What is the latest and greatest in resolving this smoothing issue?
I figured it out in Blender - I had to click on "Shading: Smooth" in the Tools tab (in Blender) before exporting, now everything is smooth as can be in BeamNG.
Sometimes that makes dark areas, weird shading, then adding edge split modifier is helpful, play with angle until you get desired result.
