The Class 423 EMU is a light-weight articulatedelectric railcar for S-Bahn commuter networks in Germany. The train has similar dimensions to its predecessor, the Class 420 EMU, but is significantly lighter and has one large passenger compartment, while that of the 420 is divided into three parts. The 423 additionally has six doors in each carriage (three on each side), which is down from eight on the 420 (four on each side). They are numbered from 423 001 to 423 462.
Both Munich and Frankfurt have ordered Class 423s for their S-Bahn systems since 1998; they were delivered between 1999 and 2004.
A Class 423 unit consists of four cars that share three jacobs bogies and can only be separated at maintenance facilities. The inner two cars are designated as Class 433. A 423 unit typically consists of the following cars, where x is the unit's number:
e.g. 423 194 + 433 194 + 433 694 + 423 694. Different consists usually occur when the remains of partially destroyed units are combined to form one intact EMU.