Noted for careful precision and finely-judged accuracy, Ascari was a multitalented racer who competed in motorcycle racing before switching to cars.

[5] In 1940, after he entered the prestigious Mille Miglia in an Auto Avio Costruzioni 815 supplied by his father's close friend Enzo Ferrari, Ascari eventually started racing on four wheels regularly.

When Italy entered World War II, the family garage, by now run by Ascari, was conscripted to service and maintain vehicles of the Italian military.

[5] During this period, he and his partner fellow racing driver Luigi Villoresi established a lucrative transport business, supplying fuel to army depots in North Africa.

Formula One regulations were introduced by the FIA in 1946, with the aim of eventually replacing the pre-war Grand Prix structure.

The team boss Enzo Ferrari had been a great friend and teammate to Ascari's father, and had taken a keen interest in his successes.

At Monaco, Ascari became the youngest driver to score points and a podium position in Formula One at 31 years, 312 days, finishing second one lap behind Juan Manuel Fangio.

When the full 4.5-litre Ferrari 375 F1 arrived for the 1950 Italian Grand Prix, the final round of the championship, Ascari gave Alfa Romeo their sternest challenge of the year before retiring; he then took over teammate Dorino Serafini's car to finish second.

[2][16] Returning to Europe, he then won the remaining six rounds of the series to clinch the world title (also taking five non-championship wins) and recording the fastest lap in each race.

[3][18] Ascari won three more consecutive races to start the 1953 season, giving him nine straight championship wins (not counting Indy) before his streak ended when he finished fourth at the 1953 French Grand Prix, which proved to be highly competitive.

[2][3] As their car was not eventually ready for the final race of the season, Gianni Lancia allowed him to drive twice for Maserati, sharing the fastest lap at the 1954 British Grand Prix,[19] and once for Ferrari.

Ascari also won the Mille Miglia that year,[3] driving a Lancia sportscar, surviving the dreadful weather and the failure of a throttle spring, which was temporarily replaced with a rubber band.

[20] When the Lancia D50 was ready, Ascari took pole position on its debut, the 1954 Spanish Grand Prix, and led impressively early on and set fastest lap before retiring with a clutch problem,[21] meaning a full season of competing against Fangio's previously dominant Mercedes was much anticipated.

While waiting for the Lancia car, Ascari had to take guest drives for Maserati and Ferrari, and he finished the season without completing any of the four Grands Prix he entered.

[23] During the 1955 Monaco Grand Prix on 22 May, Ascari crashed into the harbour through hay bales and sandbags late in the race after missing a chicane while leading, reportedly distracted by either the crowd's reaction to Stirling Moss' retirement or the close attentions of the lapped Cesare Perdisa behind.

Whatever distracted him, he approached the chicane too quickly, and chose the only way out and took his D50 through the barriers into the sea, missing a substantial iron bollard by about 30 cm.

The corner where the accident happened was renamed in his honour, and was subsequently replaced with a chicane called Variante Ascari.

[17] In 2001, the Swiss newspaper Rinascita published the story of Angelo Consonni, who was seven years old at the time of Ascari's death and was with his grandfather near the Curva del Vialone.

[27] Motor racing fans from all over mourned, as Ascari was buried next to the grave of his father in the Cimitero Monumentale in Milan, to be forever remembered as one of the greatest racers of all time.

"[17] Upon Ascari's death, his friend and rival Juan Manuel Fangio lamented: "I have lost my greatest opponent.

"[3] Ascari's death is often considered to be a contributing factor to the withdrawal of Lancia from motor racing in 1955, just three days after his funeral (although the company was also in considerable financial trouble, needing a government subsidy to survive), handing his team, drivers, cars, and spare parts over to Enzo Ferrari.

[3] His father's death helped fuel Ascari's deeply superstitious nature as he avoided black cats, was concerned about unlucky numbers, and did not allow anyone to touch the briefcase that contained his racing apparel, which included what he believed to be his lucky blue helmet and T-shirt, the goggles, and gloves.

For example, Enzo Ferrari said: "When he had to follow and pass an opponent, he evidently suffered, not from an inferiority complex, but from a nervousness that did not let him express his true class.

His double chin and slightly chubby frame brought to mind a Milanese baker more than the lean, pinched athletes of the modern age.

With his pale blue shirt and matching helmet, Ascari cut a distinctive figure in the scarlet Ferraris of the early 1950s.

He sat upright, hunched slightly forward, closer to the large steering wheel than many of his rivals, his elbows forming sharper angles.

[40] His rivalry with Juan Manuel Fangio was one of the greatest in Formula One; from 31 starts each, they combined for 27 wins, 30 pole positions, and 27 fastest laps, some of which were shared with others.

[29] Despite his short career, having fewer Grand Prix starts than any other World Champion,[17] Ascari is generally considered among the greatest Formula One drivers.

[44] Similar objective mathematical models,[45][46] such as Eichenberger and Stadelmann (2009, 12th when the 40 races started criteria is dropped), original F1metrics (2014, 9th),[47] FiveThirtyEight (2018, 19th), and updated F1metrics (2019, 5th), consistently put Ascari among the top 20 greatest Formula One drivers ever.

[50] Into the 21st century, Ascari continues to hold several Formula One records,[29] some of which have since been equalled by fellow World Champions, such as Clark, Nigel Mansell, Sebastian Vettel, and Lewis Hamilton.