Since January 1, 2006, he succeeded Jürgen Schrempp as Chairman of DaimlerChrysler (now Daimler AG), being succeeded in the position of Chrysler Group CEO by Thomas W. LaSorda.
Since leaving DaimlerChrysler, Castaing has served as a member of the board of directors for multiple manufacturing and automobile companies, including Exide, the battery company, Durakon Industries, NextEnergy, Reynard Motorsport, and Valeo.
In 2006, it was reported that an initiative called Project Kimber, led by David James, had entered talks with Nanjing to buy the MG brand in order to produce a range of sports cars based on the discontinued Smart Roadster design by DaimlerChrysler.
The company's licenses include those from Hummer, Ford, General Motors, DaimlerChrysler, The Fast and the Furious as well as proprietary designs.
The meeting was attended by 50 government officials and business leaders from Canada, the U.S. and Mexico, including officials from the Canadian Privy Council Office, the Mexican Presidency, the U.S. Department of Homeland Security and corporate reps from ExxonMobil, DaimlerChrysler, Ford, Tyco, and FedEx.
In 2006, David James entered talks with MG Rover's new owners the Nanjing Automobile Group to buy the MG brand in order to produce a number of sports cars based on the out of production Smart Roadster design following discussions with DaimlerChrysler to buy the Roadster's design, technology and equipment for approximately £13 million.
At the time of the acquisition Bonar Plastics produced parts for at least 15 industries and blue-chip customers include DaimlerChrysler, Caterpillar, John Deere, Peugeot, Renault and Volvo.
Following the 1998 merger of Daimler-Benz and Chrysler Corp. (which became "DaimlerChrysler"), Renntech began expanding into the Chrysler category - beginning with the Chrysler Crossfire, a car based heavily on Mercedes-Benz SLK components (a logical move, as Chryslers began to utilize more Mercedes-Benz parts, more of Renntech's components became compatible).
New cars and trucks are a major segment of their cargo, and vehicles are shipped for Ford, DaimlerChrysler and General Motors.
The company has done contract specialized welding for automotive companies, including DaimlerChrysler, Porsche and BMW as well as work for aircraft manufacturers, including Scheibe Flugzeugbau and Sauer aircraft engines, and aviation museums, such as the Musée de l'Air, Deutsches Museum and the Technikmuseum Speyer.