1955 Formula One season

The 1955 Formula One season was the ninth season of FIA Formula One motor racing. It featured the sixth World Championship of Drivers, which was contested over seven races between 16 January and 11 September 1955. The season also included several non-championship races for Formula One cars.

Juan Manuel Fangio won his second consecutive World Championship title. It was his third in total, a record that would not be beaten until Alain Prost in 1993. This was the last championship for a Mercedes driver until 2014.

The season was coloured by tragedy. Two drivers were killed during the 1955 Indianapolis 500: Manny Ayulo and Bill Vukovich, winner of the two previous editions. Italian Mario Alborghetti died at the non-championship Pau Grand Prix. Alberto Ascari, World Champion of and, was killed while testing a Ferrari 750 Monza at Monza. And ex-Formula One driver Pierre Levegh was killed in the 1955 Le Mans disaster, along with 83 spectators. This would lead to the cancellation of four F1 Grands Prix.

Teams and drivers
The following teams and drivers competed in the 1955 FIA World Championship. The list does not include those who only contested the Indianapolis 500.

Team and driver changes

 * Stirling Moss moved from Maserati to Mercedes, like Juan Manuel Fangio had done already during the 1954 season.
 * Maserati hired Jean Behra from Gordini, after which the French team reunited with Robert Manzon, their driver from and the years before.
 * Vanwall hired Mike Hawthorn from Ferrari, so Peter Collins moved to Owen Racing Organisation, which would later become British Racing Motors.
 * Lancia had made their debut at the end of and entered the 1955 season with full-time ambitions. They were able to hire top-class drivers Alberto Ascari, Luigi Villoresi and Eugenio Castellotti.

Mid-season changes

 * Maserati driver Sergio Mantovani lost a leg in a crash during practice for the non-championship Valentino Grand Prix. The team hired Cesare Perdisa, who finished third on his debut.
 * Peter Collins had been driving a Maserati 250F for Owen Racing Organisation when Maserati's team leader, impressed with his results, offered him a seat at the works team, starting at the Italian Grand Prix. However, Collins parted with the team after just one race, as Ferrari offered him a seat for.
 * André Simon substituted for Mercedes driver Karl Kling in the Monaco Grand Prix.
 * Double World Champion Alberto Ascari lost his life while testing a Ferrari 750 Monza at Monza. Along with serious financial troubles, this led to Lancia's team owner to halt operations and hand all assets to Enzo Ferrari. Ferrari brought back Mike Hawthorn to drive, after the Brit had spent half a year with Vanwall.
 * The 1955 24 Hours of Le Mans did not only see tragedy during the race: in Friday practice, Élie Bayol (driving in F1 for Gordini) had to avoid two spectators crossing the road. This caused him to have a severe crash, suffering a fractured skull and broken vertebrae. He was out of racing for the rest of the year, so the Gordini team hired sports car and rally driver Hermano da Silva Ramos.
 * Gordini's team manager Jean Lucas took the wheel in the Italian Grand Prix, because Robert Manzon was unavailable.

Calendar changes

 * The Monaco and Dutch Grand Prix returned to the calendar after they had been run for the last time in and, respectively.
 * The British Grand Prix was moved from Silverstone to Aintree, in keeping with the event-sharing arrangement between the two circuits.

Cancelled rounds
In the aftermath of the 1955 Le Mans disaster, it was decided to reschedule the French Grand Prix from 3 July to 25 September. It was later cancelled, along with the German, Swiss and Spanish rounds.

The circuits at Pedralbes and Bremgarten were never used again for racing. Motor racing was banned altogether in Switzerland until the 2018 Zürich ePrix.

Rounds 1 to 3
For the third year in a row, the championship opened with the Argentine Grand Prix. José Froilan González started on pole position. The Argentine had been a full-time Ferrari driver in, but it would be his only race this year. Next to him on the front row started two double World Champions: Alberto Ascari in the Lancia and Juan Manuel Fangio in the Mercedes. Fangio took the lead at the start, but lost it to Ascari on lap 3. Teammate Stirling Moss went from eighth to third, while behind them, drivers and cars were beginning to succumb to the heat of. On lap 21, Ascari crashed out by himself, leaving González in the lead. However, he was still recovering from his accident in the 1954 RAC Tourist Trophy and got exhausted. Fearing he could not hold Fangio behind, he pitted to hand the car to teammate and 1950 World Champion Nino Farina. Fangio pitted as well, for new tyres and to cool off, while Moss retired due to a vapor lock in the fuel pump. This left another local driver, Roberto Mieres in the Maserati, in the lead after starting sixteenth. Sadly, his fuel pump faltered as well and he spent 10 minutes in the pits, coming home in fifth. Besides Mieres, Fangio would be the only classified driver not to have switched cars during the race, and went on to win. Two Ferraris completed the podium, but each had seen three different drivers behind the wheel, so Fangio had an immediate lead in the championship.

The Monaco Grand Prix returned to the calendar after three years and was given the honorary title of European Grand Prix. A new rule to qualifying had been added: only the times recorded in the first practice session on Thursday afternoon would count for the front row of the grid and, thus, for pole position. The rest of the starting places would be decided by the remaining sessions on Friday and Saturday morning. This was done to entice spectators to come and watch every session, but it was an unpopular idea with the drivers. Fangio set the fastest time, ahead of Ascari and Moss, so they could relax and use the remaining sessions to try out car set-ups for the race. At the start of the race, Fangio held on to the lead, but Ascari fell back. Moss took second place after a few laps and was slowly closing up to his teammate in front. After the two drivers behind Moss pitted, Ascari was left in a lonely third place until, at half-distance, Fangio stopped on track with a broken transmission and, on lap 81, Moss's engine blew up. Ascari took the unexpected lead of the race, but mere seconds later, crashed coming out of the harbour chicane and plunged into the water. He was lucky to escape with just a cut on the nose. Maurice Trintignant took the win for Ferrari, the first of his career, ahead of Eugenio Castellotti for Lancia and Cesare Perdisa in Jean Behra's Maserati.

The Indianapolis 500 was included in the Formula One championship, but no F1 drivers attended. Bob Sweikert won the race.

In the Drivers' Championship, Maurice Trintignant (Ferrari) was leading with 11$$\tfrac{1}{3}$$ points, ahead of Juan Manuel Fangio (Mercedes) with 10 and Bob Sweikert (Kurtis Kraft) with 8. Sweikert would not compete in any other rounds.

Rounds 4 to 6
Four days after the Monaco Grand Prix, double World Champion Alberto Ascari was tragically killed in a test session at Monza. Further burdened by financial troubles, the Lancia team was left with two cars and just one driver. Soon, all assets would be merged into the Ferrari team, but this did not stop Eugenio Castellotti from scoring his first career pole position in the Belgian Grand Prix. The Mercedes cars of Juan Manuel Fangio and Stirling Moss started beside him on the front row. Championship leader Maurice Trintignant started down in eleventh out of thirteen. At the start, Fangio and Moss quickly took the lead and never looked back. Castellotti retired on lap 16, allowing 1950 World Champion Nino Farina to finish third for Ferrari.

On 11 June, the 24 Hours of Le Mans took place and many F1 drivers participated. During the race, Pierre Levegh crashed into the spectator area, killing 83 people and injuring at least 120 others. This led the FIA to postpone the French Grand Prix. However, the Dutch Grand Prix was next on the F1 championship and went on undisturbed. Mercedes managed to occupy the front row with Fangio, Moss and Karl Kling. At the start, Luigi Musso put his Maserati into second position, but was outbraved by Moss. Kling tried his best to keep up with the leading trio but, on lap 21, spun off and retired. Fangio and Moss scored another one-two finish, a minute ahead of Musso. This was the first race since the 1950 French Grand Prix that none of the cars on the podium were powered by a Ferrari engine.

For the British Grand Prix, Stirling Moss scored his first career pole position in front of his home crowd. Fangio started second, Jean Behra third for Maserati. The second row was filled by two more Mercedes: Karl Kling and Piero Taruffi. Fangio had the best start, but Moss regained the lead on lap 3, his car set up with a lower top speed but better acceleration out of the corners. Behra retired on lap 10, handing the top four positions to Mercedes, with Fangio once again in front. A couple of laps later, Moss retook the lead, grew his advantage to ten seconds and set a new lap record. Unused to having the team leader behind him, Moss looked back on the last lap and hesitated. But Fangio hang back, two tenths behind, leaving the home hero to take the win.

In the Drivers' Championship, Juan Manuel Fangio (Mercedes) led with 33 points, ahead of Stirling Moss (Mercedes) with 22 and Maurice Trintignant (Ferrari) with 11$$\tfrac{1}{3}$$ points. After the British Grand Prix, the German, Swiss, French and Spanish Grand Prix were cancelled, in the aftermath of the 1955 Le Mans disaster. This left just one race in the championship and effectively handed the title to Fangio.

Round 7
The Italian Grand Prix was run on the Monza layout including a new steep banking. Nino Farina crashed in practice when his rear tyre came apart under the load of the banked turn and the heat of the sun. He escaped unhurt but his Ferrari-run Lancia was written off, and although Sunday was substantially cooler, the other Lancia was withdrawn as a precaution. Like in Zandvoort, Mercedes-Benz in Formula One occupied the front row in the order of Fangio, Moss, Kling. Moss took the lead at the start, but gave way to his Argentinian team leader before the first lap was run. The fourth Mercedes of Taruffi went from ninth to fourth, the team repeating their procession run from last race. However, Moss pitted on lap 19 for a new windscreen and subsequently retired on lap 28 when his engine cut out. Kling's gearbox broke and he retired as well, leaving the German team worried, but Fangio and Taruffi finished the race untroubled, scoring another Mercedes 1-2, ahead of Eugenio Castellotti for Ferrari.

Juan Manuel Fangio (Mercedes) had collected 40 points and won his third Drivers' Championship, his second in a row. Teammate Stirling Moss was second with 23 points and Eugenio Castellotti third with 12. Mercedes withdrew from F1 after this season, marking it the final race until the team's revival in 2010, their final win until the 2012 Chinese Grand Prix and final championship title until.

World Championship of Drivers standings
Points were awarded to the top five classified finishers, with an additional point awarded for setting the fastest lap, regardless of finishing position or even classification. Only the best five results counted towards the championship. Shared drives result in shared points for each driver if they finished in a points-scoring position. If more than one driver set the same fastest lap time, the fastest lap point would be divided equally between the drivers. Numbers without parentheses are championship points; numbers in parentheses are total points scored. Points were awarded in the following system:
 * Italics indicates the fastest lap (1 point awarded – point shared equally between drivers sharing fastest lap)
 * Bold indicates pole position
 * † = Car driven by more than one driver

Non-championship races
Other Formula One races were also held in 1955, which did not count towards the World Championship.