Trucks are valuable. Even if you didn't want the truck, you could sell it. Engineers work to find ways to turn worthless stuff to things of value. Mechanical engineers design the body, suspension, and drive train. Electrical engineers design the radio, the lights, the cruise control and the computer that controls the engine.
Chemical engineers turn gunk into oil, gasoline and plastics.
Civil engineers design the roads the trucks travel on. Industrial Engineers are responsible for finding better ways to make and do things. Once the car is designed, it has to be built. The Industrial engineer designs the systems and processes that allow trucks to be affordable consumer goods instead of luxory items. They strive to find ways to make things that are better, cost less, and are easier to get and use.