The upcoming open betas for the new game updates of Euro Truck Simulator 2
and American Truck Simulator are coming with a new feature: advanced trailer coupling.
They say a picture is worth a thousand words and a video can show even more,
so let's take a look at it first:
The new trailer coupling feature is optional - you need to enable it in the game's options to adjust
the game's default trailer coupling behavior. Make sure to consider your precise reversing skills before doing so! 
The standard trailer coupling allowed for quite some room in the relative positions of the kingpin and the fifth-wheel.
You could also "cheat" it by approaching the trailer from an angle.
The new trailer coupling option uses full physical collision simulation for the kingpin and fifth-wheel
- you will be faced with the same challenge as a real truck driver.
Expecting this precision from a newbie player may be too intimidating, so we are keeping the standard simple coupling as a default,
but we know that a lot of our experienced truck sim players are asking for more realism,
and we hope that you will appreciate that we are improving the game in this regard step by step.
In addition to the kingpin/fifth-wheel simulation, we have also added an additional visual treat to
several trailers in the game, with an animation of raising the trailer landing gear.
(If you have really sharp eyes, you may notice something in the video which is
also a teaser for a whole bunch of new tuning content coming to Euro Truck Simulator 2 soon)
Source: http://blog.scssoft.com/