Private equity-backed DealerSocket Inc. is adding Dealertrack Technologies Inc.'s (Nasdaq: TRAK) Inventory+ business for $55 million.

Inventory+ provides inventory management services, including AAX and ECarlist, used by car dealers.

DealerSocket, headquartered in San Clemente, California, provides marketing, sales, service, customer experience and data mining-technology to car dealerships. The company has been backed by San Francisco private equity firm Vista Equity Partners since May 2014.

Under Vista’s ownership, DealerSocket has made several other add-on acquisitions, including AutoStar Solutions in May, Finance Express in February, and DealerFire in January.

The deal comes as Cox Automotive Inc. is in the process of buying Dealertrack, in a deal announced in June. The Inventory+ transaction requires approval from the U.S. Department of Justice, which is reviewing the Dealertrack-Cox deal.

Dealertrack has made acquisitions before and picked up car technology business Vintek for about $53 million in 2013.

The automotive industry has been a driving a slew of M&A transactions recently. Earlier in August, Antifreeze-maker Old World Industries LLC agreed to buy the automotive lighting business of Eiko Global LLC. In July, Palo Alto, California private equity firm HGGC said it will invest in car software business Dealer-FX.