Viewport volumetric occlusion

[TomGore]

Sometimes objects don't occlude the volumes. What can be the reason? It's hard to see actual internal explosion smoke effect when car is not occluding it. I've tried with inverting normals or adding shell modifier, but no help. Viewport clipping or scene scale - no help.
Any ideas how to fix?

[Svetlin.Nikolov]

Unfortunately this is all that 3ds max's viewport can do at the moment. The alternative would be for you to use Active Shade which is much slower.