In 1965, Sayer developed the body aero style for Jaguar XJ13, a mid-engined Jaguar sports racing car that was intended for competition at Le Mans. Cost constraints and a rule change at Le Mans meant the XJ-13 was never driven in international competition, but it exemplified all of the classical Sayer sophistication in aerodynamics as his earlier work. In 1971 the XJ 13 prototype was brought out of storage to help promote the new V12 E-Type when it was largely written off in a major crash. The car was rebuilt in 1972/73 albeit with changes from the original — losing some of the classic lines in the process.