Detroit Diesel Corporation (DDC) is an American diesel engine manufacturer headquartered in Detroit, Michigan, United States and a subsidiary of Daimler Trucks North America, itself a wholly owned subsidiary of the German Daimler AG. The company manufactures heavy-duty engines and chassis components for the on-highway and vocational commercial truck markets. Detroit Diesel has built more than 5 million engines since 1938, more than 1 million of which are still in operation worldwide. Detroit Diesel’s product line includes engines, axles, transmissions, and Virtual Technician. Detroit engines, transmissions, and axles are used in several models of truck manufactured by Daimler Trucks North America. Detroit Diesel consists of two divisions. The off-highway division, which is owned by Tognum, is a wholly owned subsidiary of Engine Holding GmbH, a joint venture of Daimler AG and Rolls-Royce Group plc. The on-highway division is owned by Daimler AG.