Nothing. Hertz did not have an available car from me at the location my reservation time, even though I made AND PAID FOR the reservation in advance. The location not only ran out of cars hours before my reservation, but they did not think to even call me to tell me that they will not be able to honor my reservation. I had to commute almost two hours to reach the Hertz location. I only found out AFTER reaching the Hertz location that my reservation would not be honored. The location also refused to assist me with my dilemma. I am STILL actively trying to get my money back for a service they refused to provide.
Confirm the location will have a car when a reservation is made in advance. I made the reservation over a week in advance. There is NO REASON AT ALL for Hertz to not have a car ready for me when I arrived.