The Jaguar D-Type is a sports racing car that was produced by Jaguar Cars Ltd. between 1954 and 1957. Although it shares many of its mechanical components with the C-Type, including the basic Straight-6 XK engine design, the structure of the car was radically different. The innovative monocoque construction brought aviation industry technology to competition car design, together with an aeronautical understanding of aerodynamic efficiency. D-Types won the Le Mans 24-hour race in 1955, 1956 and 1957. After Jaguar temporarily retired from racing as a factory team, the company offered the remaining unfinished D-Types as XKSS versions whose extra road-going equipment made them eligible for production sports car races in America. In 1957 25 of these cars were in various stages of completion when a factory fire destroyed nine of them. Total D-Type production is thought to have included 18 factory team cars, 53 customer cars, and 16 XKSS versions.