The most recent update to ZDSimulator fixes some bugs, adds some updates all around, and brings some overall smoothness to the simulator.
Fixed are the visual issues with how the train follows the track path; alignment of the wheels to the rail objects is much more consistent now. (Prior versions tended to allow the train and bogies to jerk on and off of the rails.) Over the course of several prior updates, a visual bug had caused the train, and particularly the first unit following the lead locomotive, to oscillate forward and back rapidly. This is now fixed, so the train appears to move fluidly in exterior view and in the rear-view mirrors.
There has been more work on improving the cab view and locomotive graphics overall. Another electric locomotive has been added, complementing a diesel unit added in a prior update. Station names show on the track profile, which is a welcome addition.
Download the 4.9.8 update from the ZDSimulator site; as always, the activation code will have to be updated as in prior updates.