Car's displacement is 20 miles
The shortest path covered by a particle is called its displacement. It is given that, a car drives 16 miles south and then 12 miles west.
From the attached figure, OA = 12 miles
OB = 16 miles
So, their resultant is equal to the displacement, i.e. AB. So,
AB = 20 miles
So, the car's displacement is 20 miles. Hence, this is the required solution.