아! 쿠폰이 6/15까지라서 아마 렌트카 6/15까지 빌리는 여정만 가능한지 아니면 6/14, 6/15일이 포함되면 괜찮은지는 안해봐서 모르겠네요. 이 부분을 테스트 해봐야 겠네요.

요거 전화로 기한 연장이 가능한지 한 번 물어보세요. (free day 쿠폰 종류에 따라 다를 수 있지만) 저도 전에 한 번 1년 연장 받은 적이 있습니다. 

지금 테스트 해보니까 6/15일 전에 2일만 포함되어 있으면 되네요. 2일치에 해당하는 렌트카 가격이 깎여서 나오는데 문제는 이 쿠폰이 제 계정에만 적용가능한지 그 부분을 테스트 해볼 수 가 없네요.

이건 건 T&C가 진리죠.

https://www.nationalcar.com/content/dam/National/EC-final_2017.pdf

Rental credits are non-transferable. Free Days are transferable to immediate family members of Member (e.g., spouse or domestic partner, child over the age of 21, parent) irrespective of their membership in the Program. Members may transfer up to three (3) Free Days per calendar year. Once transferred, Free Days cannot be returned to Member's account. Free Days may be redeemed electronically when submitting a reservation request for a vehicle on nationalcar.com, or customer may call 1-800-CARRENT (1-800-227-7368). (Depending on your country of residence, this call may be an international call and may be subject to the relevant charges depending on your operator.) No paper certificates will be issued for Free Days. Free Days can only be used on National Car Rental brand reservation requests at participating National Car Rental brand locations in the United States, Canada, Australia and Latin American Caribbean countries (and, in Europe, for National Car Rental brand reservations serviced by Enterprise). Free Days are combinable up to three (3) consecutive days maximum on one rental. Customers may redeem Free Days for periods of nolonger than three (3) Free Days per rental transaction. These Free Days do not include charges that are not included in the base rates of the particular applicable jurisdiction, such as (i) taxes, assessments, use fees or other governmentally imposed, authorized or permitted surcharges or pass-throughs; (ii) license recoupment fees, airport fees and concession recoupment fees; (iii) service charges and fees; (iv) vehicle license recovery fees; (v) damage waiver, the cost of optional insurance products, fuel charges, optional upgrades, underage driver's fees, infant seats or other optional items; (vi) charges or drop-off charges for one way rentals; or (vii) tolls or parking violations. Free Days are redeemable for passenger vehicles only. Transferred Free Days are valid for one (1) year from the original month of transfer