[6] A public poll over the livery of the S-Bahn trains was held in Frankfurt, Munich and Düsseldorf.

Munich received blue trains, Düsseldorf chose orange and Frankfurt also received orange liveried trains due to economic reasons, despite opting for the red livery.

[7] Units used on Munich S-Bahn services to the airport received a light blue livery.

[3] Between April 2005 and January 2006, two trains (420 400 and 420 416) received an experimental refurbishment at DB Krefeld-Oppum works, and were branded as "420Plus".

[3] Changes to the interior included new seating, the addition of air conditioning and windows in the inner car ends, passenger information displays and push-button door openers.

The current of the traction motors is controlled steplessly over two asymmetrical semi-controlled rectifier bridges in sequence.

[9] These former Rhine-Ruhr S-Bahn units will be fitted with Linienzugbeeinflussung (LZB), which enables them to run on the Stammstrecke.

[4] These SL Class X420 trains underwent modifications, which included changes to the cabs, the addition of Swedish Automatic Train Control, and boards to cope with the lower platform heights in Stockholm.