One difference between the Paris Métro and the subway in New York City is that the doors of the métro do not automatically open. On the older cars, there is a little latch that you have to flip to get the door to open, and on the newer cars there is a button you press. This probably saves some energy, and certainly when it’s colder out this means the cars can stay warmer, because if no one needs to get off a stop, then the doors remain closed. Another difference is that the release to allow the doors to be opened is triggered at some point well before the train actually comes to a complete stop. This means that if you flip the handle early, you can jump off a train that is still-moving (although not very quickly). I like to think I can pick out real Parisians as they are the ones that open the door with an insouciant flick of the wrist, and then spring off the slowing car, landing neatly on the platform with nary a feather ruffled.