Further development of the 125 began in the year of its debut, 1947. Its displacement was first upped from 1,500 cc to 1,900 cc, and the resulting model was christened the 159 as the cars took their names from their engine’s single cylinder displacement.

As with the 125, the first version of the car was known as the 159 S and it made its debut at Pescara in the hands of Franco Cortese who finished second overall. The later 159 C version competed in the last race of the season in Modena but Cortese once again had to retire.

The cars' technical characteristics remained mostly unchanged with the exception of the overall displacement and, of course, engine power.