World title. The Mercedes-Benz work team pulled out of the championship after 1955 due to their crash at Le Mans, while the small Aston Martin factory team struggled to find success in 1957 and 1958 until it managed to win the championship in 1959. Notably absent from the overall results were the Jaguar works team, who did not enter any events other than Le Mans, despite the potential of the C- and D-Types. 1962 to 1965 In 1962, the calendar was expanded to include smaller races, while the FIA shifted the focus to production based GT cars. The World Sportscar Championship title was discontinued, being replaced by the International Championship for GT Manufacturers. They group cars into three categories with specific engine sizes; less than one litre, less than two litres, and over two litres. Hillclimbs, sprint races and smaller races expanded the championship, which now had about 15 races per season. The famous races like Le Mans still counted towards the prototype championship, however, the points valuation wasn't very tabular so the FIA returned to the original form of the championship with about 6 to 10 races. For 1963 the three engine capacity classes remained but a prototype category was added. For 1965 the engine classes became for cars under 1300 cc (Class I), under 2000 cc (Class II), and over 2000 cc (Class III). Class III was designed to attract more American manufacturers, with no upper limit on engine displacement. 1966 to 1981 The period between 1966 and 1971 was possibly the most successful era of the World Championship, with S (5 L sports cars ) and P (3 L prototypes) classes, and cars such as the Ferrari 512S, Ferrari 330 P4, Ford GT40, Lola T70, Chaparral, Alfa Romeo 33, and Porsche's 908, 917 battled for supremacy on classic circuits such as Sebring, Nürburgring, Spa-Francorchamps, Monza, Targa Florio, and Le Mans where the Ford's won four years in a row, in what is now considered the Golden Age of sports car racing. In 1972 the Group 6 Prototype and Group 5 Sports Car classes were both replaced by a new Group 5 Sports Car class. These cars were limited to 3.0 L engines by the FIA, and manufacturers gradually lost interest. The new Group 5 Sports Cars, together with Group 4 Grand Touring Cars, would contest the FIA's newly renamed World Championship for Makes from 1972 to 1975.