He acquired a Ferrari 166 MM s/n 0058M at the age of twenty, from a local benefactor,[4] and began racing sports cars.
[4] He eventually made his Grand Prix debut at Buenos Aires on 16 January 1955, for Lancia, but struggled in the warmer temperatures and crashed.
[4] However, he finished second at Monaco,[6] but in mid-season the team amalgamated with Scuderia Ferrari, for whom Castellotti drove for the remainder of his career.
[4] He followed this triumph by winning the Mille Miglia race in Brescia and the Grand Prix for sports cars in Rouen, France.
[4] Known for his sophisticated manners and tailored clothes, Castellotti had significantly prominent media profile in Italy for his relationship with ballerina and actress Delia Scala.
The team used modified Ferrari Tipo 553 2.0-litre engines bored out to 2.5 litres and rebranded as "Castellotti", with "Eugenio" on the cam covers.
The team competed in four events in 1960 with Italian drivers Gino Munaron, Giorgio Scarlatti and Giulio Cabianca.