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

Even though class 612 sticks to the principle of an electric tilting system (Neicontrol-E), it was newly engineered from the beginning.

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

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.