Big changes are ahead for Zipcar, Inc., the worldwide car sharing network as the company announced today that car rental giant Avis Budget Group is buying the Cambridge-based company for approximately $500 million.

Robin Chase, co-founder and former CEO of Zipcar and founder of Paris-based Buzzcar,says it’s a smart move for Avis, and a profitable one for Zipcar. But Chase also asks whether Avis’ acquisition will create a culture clash for Zipcar’s devoted members.

Car sharing is not car rental and I’ve known that from the beginning, and the question is — does Avis understand that? Will they be able to maintain a cutting edge innovation and bring together a community of people who want to be co-creators and participants in a new style of consumerism? That will be the question,” Chase said.

Avis Budget expects to generate $50 to $70 million in annual cost savings by using both companies’ fleets to meet the demands of both renters and car-sharers.

If Zipcar shareholders approve, the deal is expected to be completed by spring of this year.