Having finished the bodywork, I picked up the tyres using GW Chaos Black, while the seats were basecoated with VMC 822 German Camo Black Brown, and the canvas cover with VMC 874 USA Tan Earth.
The seats were then highlighted with VMC 940 Saddle Brown, and the top part of the backrests received a final highlight of Saddle Brown with a little VMC 820 Offwhite mixed in; the canvas cover was highlighted with VMC 821 German Camo Beige and then with a mix of the same and Offwhite, while the latter was also used to pick up the headlights.
Everything was then given a very thin wash of mixed black and brown GW inks.
The final touch, when this was dry, was to add a little weathering. To reproduce the dust that these cars would have collected running around the field, I took a chalk artist pastel (Rembrandt Raw Sienna) and passed it several times over a piece of extremely fine sandpaper. Then I applied the powder obtained (using a dry brush) in the areas where the dust would naturally accumulate.