Avis has tossed its hat into the $400 million US car sharing market by purchasing Zipcar for about $500 million. Zipcar has a reported 760,000 members in 20 major US cities.

The acquisition comes at a 45% premium over Zipcar's closing price on Dec 31 2012 with the transaction set to complete in the spring of 2013. Zipcar was formed in January, 2000 as a way to bring the popular European concept of car sharing to the US

"By combining with Zipcar, we will significantly increase our growth potential, both in the United States and internationally, and will position our company to better serve a greater variety of consumer and commercial transportation needs," said Ronald L. Nelson, Avis Budget Group Chairman and CEO in a press release.