The order will allow DB to replace the existing fleetof class 420 trains, reducing the average age of the train fleet to six years.It will also provide the additional emus required for the extension of Lines S1(Plochingen - Kirchheim) and S4 (Marbach - Backnang), and the new Line S60 fromBöblingen to Reningen.  

The new trains are part of DB's 15-year Euros 2.5 billion contract torun the S-Bahn network from 2013. Earlier this year DB was chosen by StuttgartRegional Council (VRS) to run the six-line network, which carries around330,000 passengers per day. The contract was originally tendered in 2007 andfive bidders indicated their interest, but one was disqualified for submittingthe incorrect bidding documents and four, including DB, failed to meet thecriteria VRS had set out. DB made a new offer in March 2008, which formed thebasis for discussions on the new contract.