Materials and mapping are always a challenge.
More materials can make the model more versatile, but it could become a pain for the end-user to recolor. Some people prefer to change all of the "glass" by using one material, but some people would prefer multiple "glass" materials... and other people may get annoyed that there are 10 materials, all named "glass1", "glass2", "glass3", and so on. Sure, Poser 6 makes it easy to copy & paste material settings, but it still takes time to paste the settings to all 10 glass materials.
 
The Panel Van already has 32 materials. For some people, this may not be enough, for others, this could be too many.
 
So, I'm not sure what the correct answer is. ;)

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