Ferrari began producing cars as a manufacturer in 1947. Enzo Ferrari had established Auto Avio Costruzioni in 1939 after leaving Alfa Romeo, and that company built its first car, the Auto Avio Costruzioni sob, in 1940. However, Ferrari's first car to carry the Ferrari name was the 125 S, completed in 1947.
That distinction explains why sources may give more than one important date. 1939 marks the founding of the company that became Ferrari, while 1947 marks the beginning of Ferrari's car production under its own name. The 125 S debuted in competition in May 1947 and used Ferrari's first V12 engine, designed by Gioachino Colombo.
The answer 1950 is a common distraction because it was the first season of the Formula One World Championship, not the year Ferrari became a car manufacturer. Ferrari entered that inaugural championship season and has competed in every season since.