So I grabbed my Aztek 430 airbrush and paint from Tamiya (Black, Light Grey and Dark Yellow) and Vallejo Model Air (their "Panzergrey") and my small compressor (a "Güde" which I bought from Ebay some time ago).
At first I did a priming overspray with Black from Tamiya to give the rest of the paint a good base on all three kinds of surface - the kit's plastic, the resin and PE parts - also for pre-shading.
Then I took the Panzergrey from Vallejo and made a first layer. Next I added some of the Light Grey to highlight the plain surfaces that are mostly uncovered in the sun (body sides, top of the enigne hood and on the rear top etc.).
A third layer, highlighting with the previous colours plus a little bit of Dark Yellow was done to increase the effect of depth on the sides and on top of the Horch 108.
But now see for yourself:
