Mercedes-Benz must grow faster than rivals BMW and Audi to meet its goal of becoming the world's No. 1 premium automaker by 2020. Mercedes is counting on Ola Kaellenius, the 44-year-old former CEO of its high-performance AMG subbrand, to lead it back to the top after slipping to No. 2 behind BMW in 2005 and to third behind Audi in 2011.