Having been signed by Toyota back in 2004, Kobayashi, currently 23, spent two years in Formula Renault in Europe, winning the Italian and Eurocup titles in 2005. After this he spent two years in the Formula Three Euroseries with leading team ASM, finishing 8th and 4th in the standings.
He replaced Williams-bound Nakajima at GP2 squad DAMS for 2008 and also took Nakajima's Toyota test driver role. Despite finishing 6th in the 2008 GP2 Asia Series, he only managed 16th in the main series. He won the Asia series last winter, but has struggled again in the main series in 2009, finishing 16th again.
When Timo Glock missed Friday practice at the Japanese Grand Prix, Kobayashi was given the chance to prove his skills in front of his home crowd at Suzuka, outpacing veteran teammate Jarno Trulli in the wet sessions. Kobayashi was the automatic choice to replace Glock for the Brazilian Grand Prix following his heavy qualifying accident at Suzuka.
A good performance will give him a good chance of racing for the team in 2010. Toyota are aiming for leading names in their cars, but have already missed out on Robert Kubica and look set to miss out on Kimi Raikkonen to McLaren. Heikki Kovalainen and Nick Heidfeld are candidates but the Japanese board would like to have a Japanese driver to stir interest back home for the Cologne-based team. That would give Kobayashi the chance, along with Nakajima, who looks set to leave Williams following their cancellation of the Toyota engine contract.