Drivers
Modern drivers are contracted to a team for at least the duration of the season, but it is not uncommon for drivers to be fired or even swapped during the course of a season. Although most drivers earn their seat on ability, commercial considerations also come into play with teams having to satisfy sponsors and suppliers. Most teams also have a spare driver, whom they bring to race weekends, in case of injury or illness to a main driver. All competitors must be in possession of a FIA Super Licence.Each driver is assigned a number. The previous season's champion is designated number 1, with his team-mate given number 2. Numbers are then assigned in order according to each team's position in the previous season's constructors' championship. The number 13 is not used.
There have been exceptions to this rule, such as in 1993 and 1994, when the current World Drivers' Champion (Nigel Mansell and Alain Prost, respectively) was no longer competing in Formula One. In this case the drivers for the team of the previous year's champion are given numbers 0 (Damon Hill, on both occasions) and 2 (Prost himself and Ayrton Senna—replaced after his death by David Coulthard and occasionally Nigel Mansell–respectively). The number 13 has not been used since 1976, before which it was occasionally assigned at the discretion of individual race organisers. Before 1996, only the world championship winning driver and his team generally swapped numbers with the previous champion–the remainder held their numbers from prior years, as they had been originally set at the start of the 1974 season. For many years, for example, Ferrari held numbers 27 and 28, regardless of their finishing position in the world championship.
Jochen Rindt is the only posthumous World Champion after his points total was not overhauled despite his fatal accident at the 1970 Italian Grand Prix.
Michael Schumacher holds the record for having won the most Drivers' Championships, with seven.
Feeder series
Most F1 drivers start in kart racing competitions, and then come up through traditional European single seater series like Formula Ford and Formula Renault to Formula 3, and finally the GP2 Series. GP2 started in 2005, replacing Formula 3000, which itself had replaced Formula Two as the last major "stepping stone" into F1. Most champions from this level graduate into F1, but 2006 GP2 champion Lewis Hamilton became the first F2, F3000 or GP2 champion to win the Formula One driver's title in 2008. Drivers are not required to have competed at this level before entering Formula One. British F3 has supplied many F1 drivers, with champions including Nigel Mansell, Ayrton Senna and Mika Häkkinen having moved straight from that series to Formula One. More rarely a driver may be picked from an even lower level, as was the case with 2007 World Champion Kimi Räikkönen, who went straight from Formula Renault to F1.American Championship Car Racing has also contributed to the Formula One grid with mixed results. CART Champions Mario Andretti and Jacques Villeneuve became F1 World Champions, while Juan Pablo Montoya won seven races in F1. Other CART or ChampCar Champions, like Michael Andretti and Alessandro Zanardi won no races in F1. Other drivers have taken different paths to F1; Damon Hill raced motorbikes, and Michael Schumacher raced in sports cars, albeit after climbing through the junior single seater ranks. To race, however, the driver must hold an FIA Super Licence–ensuring that the driver has the requisite skills, and will not therefore be a danger to others. Some drivers have not had the license when first signed to a F1 team; Räikkönen received the license despite having only 23 car races to his credit.