Mister E Bunny,
Thanks for writing. Let me assure you, no posts have been deleted or filtered. The most likely reason you are not seeing any recent posts under the automotive thread is because no one has posted recently. However, it sounds like you need to check your settings. If you go to the "Under the hood" thread and click "More options" you can change your settings to show all posts in that thread. Likely, your settings are currently showing only posts newer than two months.
If you go to the home page, you will see all of the most recent posts on the Angie's List forum and the automotive topic has not been one. If you would like to start a thread of your own, perhaps the posts in that category will pick back up.
Hope that answers your question. Let me know if you need any further assistance and thanks for using Angie's List.
Paul from Angie's List