2015 Formula One World Championship

It was the 66th Formula One World Championship recognised by the sport's governing body, the Fédération Internationale de l'Automobile (FIA), as the highest class of competition for open-wheel racing cars.

His team, Mercedes, began the season as the defending Constructors' Champion, having clinched its first championship title at the 2014 Russian Grand Prix.

The other change was the cancellation of the German Grand Prix after a venue could not be agreed upon, leaving the nation without a World Championship event for the first time in fifty-five years.

Mercedes AMG Petronas F1 Team clinched the 2015 Constructors' Championship[2] at the Russian Grand Prix, ahead of Ferrari and Williams, and ended the season with a record 703 points.

The latter was saved narrowly from liquidation in February 2015, re-entering as Manor Marussia, when new investment was secured and the team left administration after an agreement with creditors was reached.

[33][34] Following an accident during pre-season testing, Alonso withdrew from the season-opening Australian Grand Prix, and Magnussen returned as his temporary replacement.

[36] Toro Rosso changed their entire line-up: along with Kvyat joining Red Bull, the team chose not to renew Jean-Éric Vergne's contract.

[45] Max Chilton relinquished his seat, joining the Indy Lights championship,[46] while Jules Bianchi was in a coma at the start of the season and ultimately died from injuries sustained at the 2014 Japanese Grand Prix.

[47][48][49] Alexander Rossi was later drafted in by Manor Marussia to make his Formula One début at the Singapore Grand Prix, replacing Merhi.

The Spaniard returned to the team for the Russian and Abu Dhabi Grands Prix, sharing the car with Rossi for the remainder of the season.

[61][62] With both venues unwilling to host the event,[63][64] the race was ultimately cancelled, leaving the country off the Grand Prix calendar for the first time since 1960.

[52] This was tweaked after the 2015 British Grand Prix with immediate effect, to make demotion to the back of the grid the maximum penalty for engine changes.

In the aftermath of Bianchi's accident, a new procedure called the Virtual Safety Car (VSC) was introduced following trials during the last three Grands Prix of 2014.

The procedure could be initiated when double waved yellow flags were needed on any section of a circuit where competitors and officials were in danger, but the circumstances did not warrant deployment of the actual safety car.

[52] Beginning with the Belgian Grand Prix, radio communication from engineers to drivers pertaining to race starts, such as recommended torque map settings for optimal acceleration, was no longer allowed.

[76] His team, Mercedes, began the season as the defending Constructors' Champion, having clinched its first championship title at the 2014 Russian Grand Prix.

It was the first season since 1994, when Alain Prost retired from the sport following his fourth and final World Drivers' Championship title in 1993, that the field did not contain a number one car.

[83] On physicians' advice, Alonso elected to sit out the opening round in Australia, prompting the team to replace him with Kevin Magnussen for the race.

[90] Renault countered with their own threat to pull out of Formula One as an engine supplier if its reputation continued to be damaged or if its participation was otherwise not profitable to the company.

[96] With McLaren's longest continuous testing session lasting twelve laps in Montmeló – a total of 56 kilometres (35 mi), a sixth of a total Grand Prix distance – before running into engine trouble, Honda elected to detune the power units for the opening Grands Prix in an effort to improve reliability and longevity while the manufacturer worked to improve these areas before homologation.

[103] After the team's arrival in Australia, while assembling the cars, it was discovered that their computers had been wiped completely clean of all data in preparation for auction,[104] and they ultimately could not compete in the Grand Prix.

[92] Manor Marussia continued to show signs of consistency, with both cars qualifying within 107%, starting, and finishing both Grands Prix in China and Bahrain.

Lewis Hamilton had scored ninety-three points out of a possible one hundred, giving him a twenty-seven-point lead over his teammate Nico Rosberg entering the eight-race European portion of the season.

[112] Rosberg quickly cut into Hamilton's championship lead by securing victories in Spain (reducing his deficit to twenty points) and Monaco.

[116] At the following Grands Prix in Canada,[117] Austria,[118] and Britain,[119] Mercedes put to rest the criticism following the result in Monaco[120] through finishing first and second in the next three races, extending their championship lead to 160 points over Ferrari.

[121] Honda continued to have reliability issues and, up to the British Grand Prix, suffered nine retirements and two failures to start due to power unit problems, translating to only seven overall finishes out of 18 possible results.

[138] A victory in the United States, with Rosberg and Vettel finishing second and third respectively, secured the third Drivers' Championship for Hamilton with three races left to run.

[146] Sauber's early season preparations were disrupted by a series of legal challenges from the former Caterham driver Giedo van der Garde, who claimed the team had reneged on a contract that was signed in June 2014.

[149] Van der Garde later agreed not to participate in the event, with the driver and team settling the dispute for an undisclosed sum and terminating the contract following the first round.

[153] Points were awarded to the top ten classified finishers in every race, using the following structure:[157] In the event of a tie, a count-back system was used as a tie-breaker, with a driver's best result used to decide the standings.