Wiener Linien commissioned Siemens at the end of 2017 with the delivery of 34 fully automated metro trains. The contract also includes the maintenance of the trains for a period of 24 years and an option for an additional eleven trains. The "X cars" will be operated fully automated on the new U5 line in Vienna beginning in 2024. The trains can also operate semi-automated or manually on previously existing lines. Delivery of the trains is scheduled to begin in mid-2020 and to be completed by 2030. The trains will be manufactured at the Siemens factory in Vienna.

Vienna's City Councilor for Public Transport, Ulli Sima, was impressed with the progress being made in production: "The X cars are an important investment for climate-friendly mobility in Vienna. In fact, environmental protection really begins right in the production hall. The new metro trainsets are constructed with up to 90 percent recyclable materials. Their lightweight design, modern LED lighting and especially energy-efficient heating and air conditioning systems ensure even lower energy consumption. With their production at the Simmering plant, the X cars are 'true Viennese,' securing jobs in the region and strengthening Vienna as a place to do business."

Wiener Linien Managing Director Günter Steinbauer noted, "Our metro system will continue to grow over the coming years with the U2-U5 interchange, and the total volume of passengers will increase as well. To handle this expanding volume, we need additional powerful trains. The X cars can be flexibly used throughout the existing network and can run on Lines U1 to U4 with passengers as soon as they receive their operating permit."

Albrecht Neumann, CEO of Rolling Stock at Siemens Mobility: "With the advent of the X cars, we're writing a new chapter in the history of Vienna's metro system – in Vienna, for Vienna. With their state-of-the-art safety features and innovative passenger information system, the trains will set new standards for comfort and sustainability well into the future."

The air-conditioned interior of the trains will be accessible end-to-end and have a bright and pleasing design. Spacious and comfortable multifunction areas will offer plenty of space, particularly for passengers with strollers or extra luggage. Retractable gap bridges at each of the 18 doors on both sides of the train will provide barrier-free access for passengers with restricted mobility. The 111-meter train can carry up to 928 passengers.

Siemens Mobility's innovative digitalized passenger information system "Plus" (FIS+), which was also developed in Vienna and will first be used in the city, will enhance travel comfort and convenience. Information displays located above each door show in real time, before arrival at the next station, the train's planned platform position and a guide to other connections. With this information, passengers already know before arriving at the station where they must go to get to their destination, and passenger flows on the platform are optimized.

Special lightweight construction elements in the bodies and bogies significantly reduce the X car's weight and make it particularly light for its class. Electrodynamic braking to a standstill substantially reduces mechanical wear on the brakes and lowers maintenance costs. Low-maintenance, energy-saving LEDs are used for interior and exterior lighting.