The Germany Intercity-Express, which also called the ICE, is the high speed railway network that connect cities in Germany and its surrounding countries. The ICE 1, which is the first series of the German high speed train, had started it first service on 2 June 1991, from Hamburg-Altona to München Hbf. The train was designed for speed up to 280km/h, however, the service speed is only up to 250 km/h.
Why do you think the train can’t increase to it maximum speed?
Jasper's Blog on Trains 