Had to tell because you don't describe what you did. The program
is mixing parts from different images (if you have made more than one) on one vehicle.
You have to name it kubelwagen-hull, kubelwagen-hull 2, ....
Also check if you have removed all other brz out the Z folder.
For me it looks like there is somewhere a yellow car in your folder and in the program is mixing it with your texture.