Come on, people!
I think the issue is that people aren't willing to comment on anyone's threads - there's been a few recent threads with less than 5 posts. If people get a lot of constructive comments on their designs, they're likely to be motivated to participate more in this section. And in turn they'll be more likely to comment on other artists' designs.
It's kind of a circular motion.
more comments => more participation => more comments... etc. etc.
That's what I think anyway. Let's all put the effort in to make Geneva one of the best motor shows ever at CSS!