The agreement expands on a partnership initiated this fall when Cars.com signed a display advertising agreement with Yahoo that extended its inventory to Yahoo's entire publishing network.

"Where previously we were a listing-centric partnership, we've increased the scope of this partnership to include this besides listings," said Michael Yang, vice president and general manager, Yahoo Autos. "It's a more robust kind of expanded relationship on various fronts."

Chief among them is the increased number of total listings at 2.4 million, and the addition of new-car ads through Cars.com's ties to 15,000 auto dealers and classified advertisers nationwide. With 87% of the Yahoo Autos audience unduplicated from Cars.com, Yahoo also said there's little overlap between the two sites.

Yahoo Autos will also feature new editorial material via Cars.com including new-car reviews, articles featuring auto-buying tips and trends, blogs and niche sites such as Mother Proof, a site that reviews cars with moms in mind.

The autos section draws about 6 million unique visitors monthly, according to Yang, who declined to discuss financial terms of the Cars.com deal or how long it would last.

Yahoo's pact with AutoTrader recently expired, creating an opening for Cars.com to power auto classifieds on the portal. Last month, AutoTrader announced it would supply used-car and private-seller listings on kkb.com, the Kelley's Blue Book site, starting in January. The site says it has 13 million monthly unique visitors.

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