Robert Kubica is returning to Formula 1 after being confirmed as Williams' reserve and development driver for 2018.
Sergey Sirotkin has been named as Williams' second driver for the 2018 Formula 1 season.
Daniil Kvyat has been named as Ferrari's development driver for the 2018 Formula 1 season.
Daniel Ricciardo hopes for more "friction" with Red Bull team-mate Max Verstappen in 2018.
Lewis Hamilton does not believe he has the "desire" needed to be able to match Michael Schumacher's record seven Formula One crowns.