The DMU DB BR 643.2 which drives on Schnellfahrstrecke Köln-Aachen has 2 cars and is at the ends of the unit painted in blue: This train is also driving on the RB20, which drives on the sections Aachen - Stolberg (every 30 Minutes) and Langerwehe - Düren (every 60 Minutes). Between Stolberg and langerwehe, the trains drive on a seperate route next to the main line. There may be other lines between Köln and Düren where this train drives. Now a picture from the inside of the train: (This may be another 643 than the train from the euregiobahn.) If licensing is a problem because of the "euregiobahn", you may just make a train in the DB-Livery. The euregiobahn isn't a company, it's just a brand. The BR 643.2 would add a lot traffic to Schnellfahrstrecke Köln-Aachen and would be the first german DMU.