The specialized stops are an issue (and have gotten very rare), but the speed limit from the car train is an issue but especially the highly cyclical nature of

The specialized stops are an issue (and have gotten very rare), but the speed limit from the car train is an issue but especially the highly cyclical nature of the demand for car transport on night trains, much more so than normal sleeper trains. Most of the rolling stock used for transporting cars is very old and not getting replaced (because you can't recoup the cost), while there have been quite a few orders for new sleeper trains.