What role does inertia play in a car's ability to maintain its speed while traveling in a straight line?

Inertia is the tendency of an object to resist changes in its motion. In a car, inertia helps maintain its speed in a straight line by resisting any changes in speed or direction unless acted upon by an external force, such as friction or air resistance. This allows the car to continue moving at a constant speed unless the driver applies the brakes or accelerates.