Kelley Blue Book is part of Cox Automotive (Photo: Kelley)

Cox Automotive said it plans to acquire Dealertrack, a maker of automotive retail software for 4 billion dlrs in cash.

The US digital marketing group said that, together, the two companies will offer a bigger portfolio of products and services to consumers, dealers, lenders and car manufacturers.

"Integrating our platforms will be a big step forward in our shared vision of providing open, cost-effective and efficient solutions for dealers," Cox Automotive President Sandy Schwartz said in a press release.

Cox Automotive provides vehicle remarketing services and digital marketing and software products for the auto industry. The company's brands include Manheim, Autotrader,  vAuto, Xtime, ad NextGear Capital. Cox also publishes the Kelley Blue Book, the leading US pricing guide for new and used vehicles.

Dealertrack, which was founded in 2001, makes and sells software for the automotive retail industry. Its credit application network connects more than 20,000 dealers with more than 1,500 lenders. The company offers software programs for dealer management systems, inventory, finance, digital marketing and other functions.