He handed the keys to his Hyundai Accent to a start-up company called FlightCar, which offered “free” parking at an off-airport lot.

Sharing companies take over a share of the travel industry

Instead of paying $18 a day to park at San Francisco International Airport last month, Daniel Denegre tried something new. He handed the keys to his Hyundai Accent to a start-up company called FlightCar, which offered “free” parking at an off-airport lot in Burlingame, Calif., and an opportunity to earn up to $20 a day by renting his vehicle to someone else.