I use a lot of different paints... acrylics, epoxy, sometimes even paints from the shop. The soot and exhaust stains are made with a double action airbrush (Badger) and contain mostly flat black, a touch of white and brown. Practice on a painted piece of sheet styrene that is primed and coated the same color if you have not done it before. Then work quickly but purposefully.
As for panel lines, I scribe everyone, then I paint the model, and use darkened amounts of the base paint (darkened black) to make the shading. Use a double action airbrush, and a piece of flexible (read thin) styrene to literally mask the back side of the panel line off. there... instant shading.