Get a Free Second Driver Lagerquist also says that Costco Travel lets you add an additional driver to your rental car reservation for free, which is a perk you don't get with every rental agreement.

But that's not all. For eligible car rental bookings, you can add an additional driver to your reservation for free. When using your Costco membership perks to rent a car with Alamo or Enterprise ...

For example, Costco car rentals have no cancellation fees, including rentals from Enterprise; however, if you were to book a prepaid rental car with Enterprise directly and cancel the reservation ...