This is something I recently noticed, as I was not aware of. Pressing ESC to bring the pause menu also brings some interesting information related to current number of wagons, train mass and total train lenght. This information is updated each time you perform a new operation that changes that data, like coupling, so it comes to be quite handy for shunting to calculate the stop position when approaching to new coupling location, for instance, as you just need to stop at a distance from marker equal to your train lenght when moving backwards. Cheers
