Zipcar Inc.’s third-quarter profit surged as the car-sharing operator benefited from more members and continued expansion. The company also raised its full-year revenue guidance to $275 million to $279 million, from a previous $272 million to $278 million. Zipcar’s sales have notched double-digit percentage gains in each quarter since the company went public in April 2011, as membership increases and it enters new markets. Zipcar reported a profit of $4.21 million, or 10 cents.