The problem is, the devs refuse to have a timeline. So they don't feel pressure to continue, and the result is, nothing happening or at least at a very slow rate. I experience the same for myself, if I don't HAVE to, it results in not doing it at all.
In my opinion, if Scawen can work on tire physics full time, it should have been possible to finish it in 2 or 3 months. I think he's only working on it when he wants to and that is perhaps only a few hours a week. I'm afraid he lost his drive to develop LFS, and LFS will silently die....