No Despawn Mod
Please take a look at my game here on Steam ?
In the default version of the game, passenger cars and cargo trucks will despawn when they are stuck in traffic jams. This mod disables this behavior, causing real traffic jams. Cars will still despawn when they are blocking other cars or when they are clipping through them. Use Ctrl+Shift+D to toggle despawning (default is off, i.e., no despawning will happen).
To disable this mod: Disable it in the content manager and restart your game.
See this thread[forum.paradoxplaza.com] for the general discussion.
You can find the source code here[github.com]. A Thank You goes to Splendid for the toggling.