Off topic means that the topics are not in keeping with the overall theme of the site, that being cars. It does not mean anything goes with respect to keeping to the original topic, although it is a bit looser than the other forums.
The reason the on topic forum was gotten rid of was because it didn't get enough traffic. Putting the political posts in the basement gets more traffic to them, and while that does make them more susceptible to whoring, it also gets a better spread of discussion.
This is still primarily a car board, so we don't need to have a separate politics forum.