Setting fog_color should be sufficient. fog_start and fog_end are only used to tweak the intensity of the effect. d3d_fogcolors is used to tweak the color of the fog in realtime. Well, mobile graphic adapters tend to be less powerfull than the ones developed for workstations, especially the intel ones. However, I can't imagine a graphics adapter younger than a year not supporting such a basic feature like fogging. You could try usnig the command line option "-w3d". Does that help?