The distance d traveled by an object under uniformly accelerated motion while it changes its speed from v_o to v_f with an acceleration a is given by the formula:
Since the car travels initially at 16m/s and it stops, then v_0=16m/s and v_f=0. Replace those values into the formula, as well as a=-4m/s^2 to find the stopping distance for the car:
Therefore, the stopping distance for the car is 32 meters.