The Research and Technology Centre of DB AG has conducted theoretical studies and simulations on the feasibility and potential for a fly-wheel storage system in a diesel-electric regional train. In collaboration with Alstom LHB, the LIREX was developed as a test carrier. The WTZ Rosslau was commissioned to build a 6 kWh fly-wheel system. However the development of the system ran into difficulties in 2002. Therefore the LIREX is planned to enter service in December 2002 without an energy storage system. The fly-wheel is planned to be integrated as soon as a mature product is available.