dont know why I remembered that you could theoretically drive em 160 kph... and now I know why - despite the designation on the cab car of 140 kph, Linke Rheinstrecke (like when you try Mainz to Koblenz direction) allows you to go 160 kph (in HUD, as well as in-game nothing is really stopping you except sense of realism/immersion)
Reminds me of the PbZ train. If you use the BR101 Expert, several cars (a random number per run) will have faulty brakes, which must be manually bled. Maximum speed 100 km/h. If the train accelerates slowly and rolls poorly, check that the brakes are released on all cars. It's possible that the BR147 is malfunctioning.