The car air intake system is responsible for delivering clean air to the engine for combustion. It consists of several components, including the air filter, intake manifold, throttle body, and mass airflow sensor. The air filter prevents contaminants from entering the engine, while the intake manifold distributes air evenly to the cylinders. The throttle body regulates the amount of air entering the engine, and the mass airflow sensor measures the air intake volume for proper fuel injection. Upgrading the air intake system can improve engine performance by increasing airflow, but it's essential to maintain the system to prevent engine damage and ensure optimal performance.