You can create your own car games using the development platform Unity. Unity is used to create 2-D and 3-D games playable on all major phones, game consoles and operating systems.
Unity is available in a free download for Windows and Mac at Unity3D.com. This edition includes the engine with all features, is royalty-free and can produce content for all platforms. The professional edition is available for $1,500 or $75 per month. This edition includes a handful of additional features, including a team license, prioritized bug handling, access to Unity Cloud Build Pro for one year and beta access. You can also purchase add-ons for specific platforms, such as Android, iOS or Windows Phone. These cost an additional $1,500 or $75 per month each.
To create your own car game you need models of cars and environmental objects to use. These can be purchased through the Unity Asset Store. However, using another free development tool called Blender, you can create your own detailed 3-D models and deploy them in Unity for use in the car game. Blender is available for free download at Blender.org for Windows, Mac and Linux. Unity has built in support for importing Blender files. Level design, physics and control systems are handled in Unity.