New Jersey-based Avis Budget Group announced today it has acquired the Zipcar car sharing company for approximately $500 million.

Avis agreed to purchase Cambridge-based Zipcar for $12.25 per share, according to a press release issued today by Zipcar. The $12.25 is a 49 percent premium over the shares' closing price on Dec. 31, 2012.

The board of directors for both companies unanimously approved the acquisition and the deal is expected to close sometime this spring. 

Zipcar currently has two car sharing spots located in the center, triangle parking lot in Newton Centre. The company has more than 760,000 members with a presence in more than 20 metropolitan areas across the U.S., Canada and Europe. 

Once the acquisition goes through, Zipcar will operate as a subsidiary of Avis. Zipcar Chairman and CEO Scott Griffith as well as President and COO Mark Norman are expected to stay on to run the day-to-day operations of Zipcar. 

In addition, Zipcar will continue to move forward with its plans to relocate headquarters from Cambridge to Boston, the press release said.