I actively participate in a forum for a certain car model. However, as that particular model has aged the forum has gotten a lot less active. Unfortunate since there is a significant wealth of resources and information on various things about the platform (aftermarket parts, tuning, troubleshooting tips for problems, etc.).

It's on the old vBulletin platform and constantly has issues with spam bots. Although I question if the long-gone/inactive admin could've put more effort into restricting the site so bots have a harder time getting in.