Some years ago, Enterprise Rent-A-Car passed Hertz as the largest car rental company in terms of rental volume. Known as the non-airport rental car company, Enterprise recently began expanding its airport operations and now serves all of the country’s top 100 airports. Their presence at airports has moved them slightly ahead of Thrifty Rental Car, which is known for its aggressive use of frequent flyer programs. It will be interesting to see how Enterprise chooses to market to the frequent flying crowd. Might miles be in the offering?