Car rental company Avis Budget Group Inc said it will buy U.S. car-sharing company Zipcar Inc for about $500 million in cash.

The offer of $12.25 per share is at a premium of 49 percent to Zipcar's Monday close.

Avis said it expects to complete the deal in the spring of 2013.

(Reporting by Sagarika Jaisinghani in Bangalore; Editing by Supriya Kurane)