The class 430 is a four-car multiple unit for S-Bahn trains that was developed jointly by Alstom and Bombardier as the successor to the class 422 and, above all, replaced the last trains of class 420. The model was originally only planned for use in the Stuttgart network, but later the production of the 422 for the Rhine-Ruhr network was also discontinued in favor of further development. Ultimately, however, the Stadler FLIRT 3 was ordered there. A second area of application was found for it with the S-Bahn Rhein-Main.

The class 430 is based directly on its predecessor, but has improvements in many areas. In principle, the same three-phase asynchronous traction motors were used, but they and the entire chassis were further optimized in terms of smooth running, background noise and energy efficiency. Energy recovery from the electric brakes is also standard and benefits from the strong acceleration and deceleration in S-Bahn operation. The train is still running on five bogies, three of which are designed as Jakobs bogies between the individual cars. Except for the central bogie, all axles are powered. The design has been updated inside and out and includes new crash standards, LED lighting and a modern passenger information system.

As with other new rail vehicles in recent years, there were several delays in the course of certification and introduction, which in this case largely affected the locking mechanism of the doors. Finally, regular operation in the Stuttgart network could be started by the turn of the year 2013/2014 and the first tests and training courses were due in the Rhine-Main area at that time. A total of 188 trains were built up to 2017 and in 2021 production for the Stuttgart network was restarted and new trains were also ordered for the S-bahn Rhein-Main, which are to be delivered in 2023. The existing trains have been optimized in terms of software over time, which means, for example, that aggregates that are not required are temporarily switched off and the opening times of the doors have been reduced. Some of the previous classes are also being adapted to the design of the 430 series.