This line are 2or3 different services which use 2 or 3 different vehicles. 2 Services Start in Hagen, they all drive to Warburg (Westf) and every 2nd hour one train continues to Kassel Wilhelmshöhe, That are 2 Services, 1 Drives from Dortmund to Winterberg, a nice ski resort, where hard winters would make sense... As vehicles I thought of the BR 612, which is a tilting train and the BR 628. Both are DMU's since after schwerte or so there is no electified path. Since I commuted there a few years back for 4 years I can tell you that this route is really interesting with the tunnels, open and wide fields, sometimes over or underpasses and beautiful scenery. I'll attach pictures of the 612,628 and the Line of the Sauerland-Express