In real life trains can move with turned off engines after acceleration. I guess that this feature can make trains in Create more realistic - you can save fuel/electricity by riding with turned off engines because train can ride more bigger distance without turned on engines than car or something like this.
How it works? You press "W" while acceleration and after getting the right speed release "W". Train move forward but with turned off engines. Speed and distance link to track profile (rise, descent or flat track influences to speed and distance of train). On rise track train slowes and stopes fast. On descent track train accelerates and can ride big distance. On flat track train moves smooth. Distance and speed also link to mass and traction performance of train.