I am creating a short little game project and I would like to have a freeway that auto spawns cars infinitely and despawns them when they get to the end of the track.
I’m looking for an effect like this from Call of Duty: Advanced Warfare.
The player needs to be able to cross while cars are coming past them.
Any advice would be greatly appreciated 
You could use a series of mesh particle emitters.
In the simplest case, a straight highway, you just have to emmit them in one direction.
User several emitters to have different car meshes spawning. With variation in spawning time, you can make it look not so repetitive.
Just be carefull with the particle speeds, or cars will bump into each other. just make the cars on the left lanes a bit faster. That further adds to realism.
If you want the “cars” to follow the highway through a bend, you would have to use vector fields to force the particle cars a certain way, which might be quite a struggle to achive…