They are usually procured in series, but only a few (compared with cars) trains per series are built. For example, there are three configurations for Germanys c

They are usually procured in series, but only a few (compared with cars) trains per series are built. For example, there are three configurations for Germanys current top of the line ICE4 high speed train, with 37, 50 and 50 sets built. Trains seat more people than cars, and they don't spend most of their time sitting idle in parking lots, so you need fewer.