Automotive engineers are employed by car and truck manufacturers as well as parts suppliers to design and build entire vehicles or individual parts or systems. They may work on the vehicle's engine design, aerodynamics, performance and fuel efficiency, safety features, ergonomics, and more. Approximately 256,550 industrial engineers are employed in the United States, and about 3 percent work in the motor vehicle parts manufacturing sector. Automotive technicians are skilled workers who are employed by car and truck manufacturers as well as parts suppliers to help automotive engineers utilize design concepts to build and enhance the operation of entire vehicles or individual automotive parts or systems. They also work on the vehicle's engine design, aerodynamics, performance and fuel efficiency, safety features, ergonomics, and other aspects of a vehicle's operation.