What if trains could disconnect in motion?

Imagine a subway line with x number of stops. Now imagine trains in that line had equal number of cars. Each car was labelled with a different stop on that line, in sequence, with the first stop being the last car.

As the train speeds across the line the cars disconnect from behind in sequence with their own braking system to stop at the stop of their designation.

This means every passenger has only one stop per line greatly speeding up their journey.