The Ferrari 166 S was a sports racing car built by Ferrari between 1948 and 1953, an evolution of its Colombo V12-powered 125 S racer. It was adapted into a sports car for the street in the form of the 166 Inter.
Only 12 Ferrari 166 S were produced, nine of them with cycle-fenders as the Spyder Corsa. It was soon followed by the updated and highly successful Ferrari 166 MM (Mille Miglia), of which 47 were made from 1948 to 1953. Its early victories in the Targa Florio and Mille Miglia and others in international competition made the manufacturer a serious competitor in the racing industry. Both were later replaced by the 2.3 L 195 S.