I think Jeff brings up some good points related to this issue.
That said, there are a variety of other issues that cause CF's ZR-1 section to have more posters. We have tried to give our members a place to express themselves without having to worry about restrictive moderation.
We started the Corvette Babes section(a success) and the Racing section(not so much so), both of which CF banned a long time ago. Additionally Carfax requests along with other petty things CF wont allow, we have no issue with. We have also run a few contests to stimulate the forum with some success. Overall the forum is a lot more active than it use to be, but there is still plenty of room for improvement.
We will keep on trying though.