The success of TEE and InterCity service pushed these elegant diesel powered rail car trains to the limits of their capacity. They needed more power in order for 10-car units to reach speeds of 160 km/h or 100 mph. More powerful diesel motors would have been too large and too heavy, so the German Federal Railroad decided on turbine propulsion. The first class 601 powered end car was rebuilt in 1970/1971. The end car was equipped with a 2,400 hp turbine to replace the 1,200 hp diesel motor. Although it was twice as powerful, the turbine was more compact in design and used considerably more air in its combustion process.
Huge intake air, ventilation, and exhaust gas ducts filled the round nose of the powered end car. On the outside the new propulsion could be identified by the wide exhaust stack between the windows of the cab and by the additional air intakes. They ensured that the turbines took in sufficient air in both directions of travel, i.e. with a powered end car at the rear of the train.