When the engine of grand prix racing was fired up again after the Second World War, the governing body reverted to a formula that it had intended to bring into effect in 1940. Designers were presented with a choice of engine configurations: 1.5 litres supercharged or 4.5 litres unsupercharged.
At the time of its conception, the idea was to sabotage the supremacy of the state-sponsored German teams, Mercedes-Benz and Auto Union, whose all-conquering cars had been designed to meet regulations permitting supercharged three-litre engines. But for the one grand prix run under the new formula in 1939, the lucrative Tripoli race, Mercedes had ambushed the Italians, designing and constructing a couple of 1.5-litre cars in double-quick time, their speed in a crushing victory dismaying the Alfa Romeo and Maserati outfits, in particular.
Luckily for the Italians, the German manufacturers were not ready, for obvious reasons, to resume their racing activities in 1950. So, the next-best car in Tripoli, Alfa Romeo's Tipo 158, became the class of the field under the new regulations.