On 15 November 2006, Honda Racing announced the signing of Klien as their test and reserve driver for the 2007 season.
The Austrian made his debut for the Japanese works team at the Circuit de Catalunya, during the early pre-season testing during late November 2006.
 At the 2007 British Grand Prix, he replaced the injured Jenson Button for the second free practice session on Friday.
On 11 July 2007, Klien was released by Honda F1 to test with Spyker with a view to replacing Christijan Albers who was released because of sponsorship problems.
However, the seat went to Japanese driver Sakon Yamamoto.

In 2008 Klien signed as BMW Sauber's test and reserve driver for the 2008 Formula One season.
He also signed with Peugeot to race in 24 Hours of Le Mans.
Driving the Peugeot 908 HDi FAP he finished third overall with Ricardo Zonta and Franck Montagny.
In October he participated in Petit Le Mans in the American Le Mans Series, driving with Peugeot's factory drivers Marc Gené and Nicolas Minassian.

Klien remained in the position of BMW Sauber's test and reserve driver for 2009.
He also returned to Le Mans with Peugeot, finishing sixth overall in a 908 shared with Pedro Lamy and Minassian.

For 2010, Klien was understood to be an option for Sauber before the seat went to Pedro de la Rosa.
On 15 November 2006, Honda Racing announced the signing of Klien as their test and reserve driver for the 2007 season. The Austrian made his debut for the Japanese works team at the Circuit de Catalunya, during the early pre-season testing during late November 2006.  At the 2007 British Grand Prix, he replaced the injured Jenson Button for the second free practice session on Friday. On 11 July 2007, Klien was released by Honda F1 to test with Spyker with a view to replacing Christijan Albers who was released because of sponsorship problems. However, the seat went to Japanese driver Sakon Yamamoto.
In 2008 Klien signed as BMW Sauber's test and reserve driver for the 2008 Formula One season. He also signed with Peugeot to race in 24 Hours of Le Mans. Driving the Peugeot 908 HDi FAP he finished third overall with Ricardo Zonta and Franck Montagny. In October he participated in Petit Le Mans in the American Le Mans Series, driving with Peugeot's factory drivers Marc Gené and Nicolas Minassian.
Klien remained in the position of BMW Sauber's test and reserve driver for 2009. He also returned to Le Mans with Peugeot, finishing sixth overall in a 908 shared with Pedro Lamy and Minassian.
For 2010, Klien was understood to be an option for Sauber before the seat went to Pedro de la Rosa.
Christian Klien