Sure! Here's a simple example of a car racing game implemented as a single HTML file with JavaScript:
This code sets up a basic car racing game where the player can control a car using the left and right arrow keys. The car can move within the boundaries of the canvas and it is drawn as a red rectangle. The road is displayed as a gray rectangle and a white finish line is drawn at the top.
Please note that this is a simplified version and does not include advanced features such as opponents, collision detection, or scoring. You can build upon this foundation to add more complexity and improve the game as per your requirements.