With an older DC EMU such as a 4-CEP I imagine that the driving motor
car can be uncoupled from the set and run independently under its own
power, and that 2 such cars could form a 2 car train.

Are the driving motor cars of modern DC EMUs such as Networkers,
Junipers, Electrostars and Desiros independent multiple units in this
way? It seems that no set is ever run without a pantograph trailer car
- is this because the motor cars rely on the electronics or other
systems in this car, even when running from the DC 3rd rail? Or can
the motor cars run seperately from the rest of the set?

Thanks,

Dominic