Car sharing company Zipcar has raised $21 million in Series G funding. This may mean that the company is postponing their IPO. Zipcar has about 500,000 users. Zipcar filed for an IPO back in June and it is likely that they would have raised $75 million. The S1 also indicated the Zipcar would borrow $70 million under a one-year credit facility for purchasing new cars. Zipcar also recently bought their U.K. competitor Streetcar.

Zipcar, the car-sharing company based in Cambridge, MA has acquired Streetcar, a U.K. car company that has a similar business model. “When considered along with our investment in the largest car sharing company in Spain in late 2009, this transaction gives us a very strong base from which to expand to additional European markets,” stated Zipcar chairman and CEO Scott Griffith. No word on how much the financial details were, but rumor has it that Zipcar spent about $50 million. [Xconomy]