This is the gallery of all Retro Cartoon Car models available, with new and more detailed cars added every month or two. All models are royalty free to use in your game project, animation or visualization. Purchases can be made either in Unity Asset Store, or Sketchfab. You will find links to stores on page of each individual car.
Unity Asset Store downloads include texture files in .PSD format with unlocked layers. This will allow you to make any modifications necessary to make the car look individual to your project.