When the newly constructed line from Stuttgart to Mannheim went into operation on July 2, 1991, it was planned that the Airport Express Stuttgart – Frankfurt Airport would take this route. However, due to the higher speed and above all the pressure problems in the numerous tunnels on this new line, the existing cars and locomotives could no longer be used here. Along with a decrease in the running time to 90 minutes came an expansion to four daily pairs of trains that were to be run with only one locomotive. Admittedly, two train sets were required due to the short turnaround times in Stuttgart. Airtight cars repainted to Lufthansa specifications were assigned to the Airport Express with electric locomotive 103 101, also painted to match the train, from the Frankfurt/Main District.
The class 103 changed to the Lufthansa colors to match the cars in the train. Light Gray (RAL 7035) now dominated on the locomotive body and the roof hood. A narrow edge of Melon Yellow (RAL 1028) gleamed on the lower edge of the locomotive body at the transition to the bridge frame. This color continued in the upper part of the bridge frame. The older design ventilation grills kept their customary silver gray color. The lower part of the bridge frame including the buffer cladding and trucks have by contrast a dark gray color (NCS 8000). On the sides in the yellow area of the frame the lettering, "Lufthansa Airport Express", stood out and the DB emblem was located in a greatly reduced form only on the sides to the left next to the road number. Compared to the rolling stock road number 103 101 was not airtight and the schedules were therefore designed so that trains could not meet in the tunnel sections.
The short turnaround times in Stuttgart then led to a "flying change" between the two car sets, usually consisting of three cars, which played out as follows: One car set stood on a track in readiness in the Stuttgart stub end station. The Airport Express coming from Frankfurt arrived on this track, the locomotive uncoupled from that train and coupled again to the cars already standing there in readiness. A switch engine pulled the car set just arrived to the coach yard to be readied for the next run and after a few minutes, the Airport Express could depart again. Unfortunately Lufthansa halted all service at "Elevation Zero" on May 23, 1993 and road number 103 101 was thereby underway for the last time on the day before.