Originally Posted by AutoSlash

This is a question that comes up again and again, and our answer is that prepaying for your rental does not make it more likely that you will get a car vs. paying at the counter.

It's a common misconception that a prepaid reservation is somehow "guaranteed" while a pay-at-counter reservation is not. In fact, they are both guaranteed, but that doesn't mean that rental companies don't sometimes plan poorly or run into unforeseen circumstances and can run out of cars. Just because you have prepaid for your reservation doesn't mean that the rental company will "set one aside" for you. You are going to essentially be in the same boat as everyone else who has a reservation (whether prepaid or not), and we say this with almost 15 years of experience in the industry.