Is this the relevant section from the terms and conditions:

If you make a reservation for a non-prepaid rental specifying a pick-up location in the United States of America or anywhere else in the world outside Europe, the Middle East and Africa and you fail to arrive at the pick-up location by 11:59 p.m. (local time) on the specified pick-up date (or, if the location closes before 11:59 p.m., by the location’s closing time), the reservation will expire.

So I take it it will just expire?