A dozen companies were contacted by Lexus, the nation's top selling luxury marque, to help plot a road map to the brand's future.
Siegelgale's New York and Los Angeles offices will work on the initiative, which Mike Wells, vice president of marketing at Lexus, called the largest evalution since the luxury car launched in fall 1989.
The project comes as Lexus enjoys record U.S. sales even in the middle of an economic slowdown.
"We want to keep this momentum going," Mr. Wells told Advertising Age in July. "We want to clearly identify that Lexus magic. Now is the time to figure out Lexus' DNA."
A Lexus spokeswoman said Siegelgale had once been part of Publicis Groupe's Saatchi & Saatchi, which handles Toyota accounts across the globe, including the U.S. But, she added, Siegelgale split from Saatchi to pursue more Internet activity.