A more powerful Mini Cooper, dubbed the "S", was developed in tandem and released in 1963. Featuring a 1071 cc engine with a 70.61 mm bore and nitrided steel crankshaft and strengthened bottom end to allow further tuning; and larger servo-assisted disc brakes, 4, 030 Cooper S cars were produced and sold until the model was updated in August 1964. Cooper also produced two S models specifically for circuit racing in the under 1, 000 cc and under 1, 300 cc classes respectively, rated at 970 cc (59 cu in) and a 1, 275 cc (77.8 cu in), both had a 70.61 mm (2.780 in) bore and both were also offered to the public. From 1966 onwards Cooper S models featured twin fuel tanks as standard. The smaller-engine model was not well received, and only 963 had been built when the model was discontinued in 1965. The 1, 275 cc Cooper S models continued in production until 1971. Sales of the Mini Cooper were: 64, 000 Mark I Coopers with 997 cc or 998 cc engines; 19, 000 Mark I Cooper S with 970 cc, 1, 071 cc or 1, 275 cc engines; 16, 000 Mark II Coopers with 998 cc engines; 6, 300 Mark II Cooper S with 1, 275 cc engines. There were no Mark III Coopers and 1, 570 Mark III Cooper S. An agreement between BMC and Innocenti was announced in 1959 to assemble manufacture BMC cars for the Italian market.[75] The first Mini Coopers assembled in Milan from imported knock-down kits with sales of the Innocenti Mini Cooper 1300 began in March 1966.[75] It was licensed in 1973 to Spain's Authi (Automoviles de Turismo Hispano-Ingleses), which began to produce the Authi Mini Cooper 1300. The Cooper name was discontinued from the UK Mini range at this time.
