A few weeks ago, I made an unpaid Alamo reservation for some dates when I knew I'd be flying, but I hadn't chosen the flights yet.

It now turns out I'd be arriving several hours after the car pick-up time. I don't want to change the reservation, since the prices I now see are more than twice as much.

If I just show up late, will Alamo still honor the reservation? Will they change the drop-off deadline to the later time, or will I lose a few hours of rental time?

People arrive late because of flight delays all the time. But will Alamo only change the reservation time if a late flight's number was on the reservation?