Reynard Motorsport
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. He also served on the board of the Federation of American Scientists. In 2004, TRW Automotive Holdings announced the election of Castaing to the company's board of directors. He also serves on the audit committee of Amerigon (now Gentherm Incorporated).