Thor,
looks very impressive!
I´m just building a Horch in standard German Grey scheme and seeing your wonderful paint job gives me many ideas...very good timing!
I love the paintwork especially in the wheel area. What colours did you use? What was the base colour?
The only thing that comes to my mind about your weathering is that the chassis could perhaps use a sprinkle or two of the same brown tone shown in the wheel and track area. It would put the vehicle together really well!
Cheers,
Toni