McGarryBowen declined to comment. Cars.com confirmed the news.
It was believed that Cars.com plans to continue working with OMD for media-buying duties, MEA for digital, and Avenue for its b-to-b marketing efforts.
When Ad Age reported news of the review, people familiar with the request for proposal said that the site is looking to grow its traffic and revenue.
The news comes just after one of McGarryBowen's other accounts, Marriott, went into review. The agency handles that business out of New York. Last year, though, was a stellar year for the agency, which picked up big marketers such as Sears and Bud Light, both handled out of Chicago, as well as United Continental and Reebok, an account that the agency had before.
Cars.com spent a total of $29 million on domestic measured media in 2011, up from $26 million in 2010, according to Kantar Media. A large part of that budget is spent on advertising in the Super Bowl each year.