Available on Asset Store:
assetstore.unity.com/packages/tools/ai/mobile-traf…

Highly performant and easy to use traffic system that can make any driving game more fun to play in just a few clicks. No coding is required to set it up and detailed video tutorials are available.

Key Features of the asset:

High performance - 300 cars on a 2018 Android device
No coding skills required.
Traffic lights intersections support.
Priority intersections support - cars decide by themselves to wait or to enter an intersection.
Roundabout support - cars wait until the roundabout is free.
Narrow road support - cars wait until the lane is free before changing it.
Overtake - cars automatically overtake each other if the road has multiple lanes.
Building avoidance - if a car hits a building, it will try to recover itself.
Customizable car properties - acceleration, max speed, brake speed, steer angle etc.
Variable number of wheels - from 3 to as many as you want.
Automatically car assignments - made just by pressing a button.
Speed routes - set speed restrictions for some lanes or areas and all cars will follow them.
Car types - assign different types to cars and you can restrict access on some roads based on car types (ex: trucks are allowed only on the first lane and are not allowed inside the cities).
Lights support - main lights, brake lights, blinkers, reverse lights that automatically work.
Sound support - basic engine sound for each car based on acceleration and speed.
Hard shadow support - useful is you need even more performance.
Custom editor tools - a lot of editor windows to make the integration process as smooth as possible.
Simple API for advanced functionalities.
Parallel job system - for better performance.
Burst compiler - to speed up the computations.
No wheel colliders - raycasts are used for better performance and high accuracy.
Pooling system - spawns the cars around the player so you can create high density traffic with low number of used cars. Very scalable for huge environments.
Layer management - for better optimization.
Waypoints driving - it comes with an easy to use Waypoint editor, so waypoint generation is semi-automatically.
Full editor script that automatically prepares your car.
Full code is provided and fully commented, no dlls.
Works with any version of Unity above 2019.1.0 with any Unity license available.
Works with any supported Unity platforms.