The RegioSwinger is a tilting diesel multiple unit (DMU) passenger train used for fast regional traffic on unelectrified lines.

Today class 612 is back to tilting operation and forms the backbone of DB's fast regional service on unelectrified lines.

Up to four units can be connected by the Scharfenberg coupler, with the on-board computers automatically choosing the train configuration.

On July 24, 2009, a train derailed near Rudine, Croatia, with 119 passengers aboard, killing 6 and injuring 55, on the Zagreb-Split line.

[2] According to Croatian news reports, the cause of the derailment was slippery fire retardant that was just sprayed on a steep downhill section of the track, a normal practice in extreme summer heat but executed improperly using a new chemical.

Investigation continues, with questionable application of fire retardant (recently changed to "aqueous based resin liquid penetrate" TG-300 from a new supplier) emerging as the most likely cause of the accident.