Classifying costs as Materials, Labor, or Factory Overhead Indicate whether each of the following costs of an automobile manufacturer would be classified as direct materials cost, direct labor cost, or factory overhead cost: Cost Classification a. Depreciation of robotic assembly line equipment b. vs automobile engine c. Steering wheel d. Wheels e. Painting safety masks for employees working in the paint room f. Salary of test driver 9. Glass used in the vehicle's windshield h. Wages of assembly line worker