TNS Media Intelligence put domestic measured media spending for the Hyundai and Kia brands at about $735 million last year.
Aegis Group's Carat, the current media agency of record for Hyundai and Kia, has been invited to participate in the review and will defend the account, a spokeswoman said.
The review will be conducted by Roth Associates.
"We are confident that with Roth Associates supporting the review, WMG will have the best opportunity to select the right media agency to help us meet strategic needs for Hyundai and Kia, growing brands in the North American market," William Lee, chief operating officer of World Marketing Group, said in a statement.
Creative not affected
The review has no impact on Hyundai or Kia's creative agencies, which are Omnicom Group's Goodby Silverstein & Partners and independent David & Goliath, respectively.
Late last month, Hyundai's top U.S. marketing executive, Steve Wilhite, left the company. Hyundai reported flat sales through August of 325,193 vehicles, which forced the automaker to reduce its original 2007 U.S. sales projection from 550,000 vehicles by 40,000 units.