Designed for the 1956 Mille Miglia and as a replacement for the 860 Monza, the 290MM was mounted with a V12 engine with dual ignition and dry sump derived from the 4.5-litre Grand Prix. Even though this engine could be described as belonging to Lampredi school, its bore and stroke measurements were really more reminiscent of Colombo’s V12 than anything else. 
The car was an immediate success. In fact, Castellotti not only drove it home first in the Mille Miglia followed by two 860 Monzas piloted by Collins and Musso, but it also took fourth in the same race with Fangio at the wheel.