car crash

I also made this question on Reddit and i felt like i also had to make one here i hope the tags are correct

How do I make a car crash scene like with a train and a car? How do I drive or make two cars drive at the same time so I can make a real-life looking traffic crash? By the way, how do I use slow motion by using the keyboard? I know how to use it by going to the top of the screen but I would...