Mantovani was a successful young Italian businessman who went racing essentially for fun. He started racing sports cars in the early 1950s and in 1952 he finished second in class, sixth overall, with a Ferrari in the Bari GP, and second in a Lancia Aurelia in the GT class at the Pescara 12 Hours.

In 1953 he shared a 2-litre Maserati sports car with Fangio to take third in the Targa Florio, and they went on to win the Circuit of Caserta. This led to a drive in that year's Italian GP, though he had to hand his car over to Musso in the race.

Realising that he had some talent he decided to enter Grand Prix racing full time with a new Maserati 250F in 1954. Juan-Manuel Fangio won the World Championship that year in a sister car and Mantovani managed to persuade the factory to let him become a works driver. He was both fast and smooth. He finished fifth on two occasions, the German GP and the Swiss GP at Bremgarten, and took third in both the Syracuse and Rome non-championship races.

In 1955 season Mantovani crashed while testing a spare factory car for the non-Championship Turin Grand Prix on the Valentino Park street circuit. He suffered serious leg injuries and complications developed. The unfortunate Mantovani had to have his leg amputated, which ended a promising Formula 1 career at the age of only 25.

After the accident he was fitted with an artificial leg and was able to walk again although he was forced to use a walking stick. His passion for the sport did not disappear, however, and he was actively involved for many years as a member of the sporting commission of the Automobile Club of Italy.