Whoops - just saw this; would have mentioned it earlier otherwise.
# Remco :
made the stockpart list, don't know why the parts that should be the colour of a separate texture change colour too...
There's a way to fix this, at least with regard to the standard dealership, although not for the catalog. Take a look at the stock parts list for my Mustang S197 and my HSV Commodore to see what I mean - you have to use an addPart() with a texture ID parameter, instead of simply adding the parts to the stock parts list.