Audi, in conjunction with Best Buddies International today announced the anticipated celebrity attendees at this year's Audi Best Buddies Challenge: Hearst Castle on September 8. With Audi as a first-time host and title sponsor of this annual charity bicycle tour, Audi of America's Western Region director Michael Cagle, and other senior executives will welcome celebrity guests and riders, including Maria Shriver and her husband, California's governor Arnold Schwarzenegger, legendary actor and director Clint Eastwood, Lacey Chabert of Mean Girls and TV's Party of Five, The Bachelor's Andy Baldwin and Tessa Horst, celebrity trainer Kim Lyons, Gunter Schlierkamp from Beerfest and The Hulk, The Ex-Wives Clubs' Marla Maples, actor Greg German and Adrian Pasdar from TV's Heroes to the historic Hearst Castle in northern California's San Simeon Hills. Actor Rob Lowe (Brothers and Sisters, The West Wing) will lead the peloton through the first 20 miles of a challenging 100 mile ride along the Pacific Coast Highway in an Audi RS4 Friendship pace car, hand painted by noted Brazilian artist Romero Britto. Audi will also provide 35 cars to shuttle guests to and from the event.The Audi Best Buddies Challenge: Hearst Castle is a bicycle tour taking riders from Chateau Julien in Carmel to the Hearst Ranch in San Simeon. California's First Lady, Maria Shriver, will serve as Honorary Chairperson and will also ride in the event. In addition to celebrity riders, an Audi team composed of customers, executives, and members of Audi's ad agency Venables, Bell and Partners will participate. Notable cyclists such as Axel Merckx, Aaron Olsen, Kimberly Baldwin and Kim Anderson will join Audi and Best Buddies, as well. Olympic medalist and former world champion Mari Holden will return to the Audi Best Buddies Challenge for the third straight year.