Stairstepping issue in volumetric lighting

Using Movable Spot Lights as head lamps for a vehicle with Volumetric Scattering Intensity set to 12.
Also using Exponential Fog with Volumetric Fog enabled.

How can I reduce or eliminate the visible ‘stairstepping’ in my lighting?

I would like to know solution for this as well. I have banding issues in render (even in unreal) for dark, foggy and minimal lighting situations.