(N/A) According to Newton's First Law of Motion, an object remains in a state of rest or uniform motion in a straight line unless acted upon by an external unbalanced force.
If a car is moving with a constant (uniform) velocity, its acceleration $(a)$ is zero.
According to Newton's Second Law of Motion, the resultant force $(F_{net})$ acting on an object is given by $F_{net} = m \cdot a$.
Since the velocity is constant, the acceleration $a = 0$. Therefore, $F_{net} = m \cdot 0 = 0$.
This means that the vector sum of all external forces acting on the car (such as the driving force from the engine, air resistance, and rolling friction) must be zero for the car to maintain a constant velocity.