I've had some ideas on ways to revolutionize the way online car communities work over the last year or two, but have yet to implement them. The forum system can work, but in order to maintain attention spans I've found that it requires significant activity. Without that, people visit, see nothing and leave without posting their own ideas/activity, and with less activity more people leave. People want to be able to just share things that happen and quickly get responses. People only see the most popular topics and others fall away.
Facebook makes things accessible to people and quickly. People can respond quickly and see new updates all the time. There are fewer of these cars around and more people have the knowledge they need (or can find it) without needing to open new discussions. Or it's too much of a pain to ask on a forum where a response is likely to take a few hours at least versus Facebook where an answer (right or wrong) can be had in minutes.
Keeping things organized and searchable while also providing an interface that allows people to quickly respond to specific people, etc., can be quite the challenge. There is other forum software out there that I find works better for this than vBulletin. I don't particularly care for the newer versions of vB, but what we're on here is also not that up to date either, though some of the plugins we have do help, I'm not sure it's enough. In addition, I find the forums spread a bit too thin these days. While the organization is good for finding things sometimes, it means there are many forums that haven't had a post in years. I think in general, SM needs work, but also that there is the possibility it will never be that active ever again, and that is something that needs to be considered.
All said, the forum isn't dead yet, and there is a lot of good stuff here. Forums are just a different, less active, medium these days (with some exceptions of course, I am on Tacomaworld and that place is very active, but they are also still selling them in showrooms, so people have a lot of questions and sometimes the answers are more difficult to find).
Jeff