There seems to be a problem with the graphics for BR234. In some directions, there is a gap between the locomotive and the following car, while in other directions, the first car overlaps the locomotive. I remember many locomotives suffering from overlapping a while back, but I think they have been fixed. As far as I have noticed, only BR234 remains to be fixed (except maybe a few very minor cases).
Been reported in the german forum a couple of days ago:
http://www.simutrans-forum.de/forum/thread.php?threadid=6452
So someone is looking into it then?
It is on my todo list. But this weekend was entire computer-free.