Some websites may offer prepaid reservations, but be very careful when you encounter these.
Some companies--most notably Priceline and Hotwire--let you bid for and prepay for a rental car, but if you do this, you usually can't cancel or refund your rental at all. That means that even if your flight is canceled or you have a family emergency and have to cancel your trip, you're out the money you paid for your car. These rates may look low up front, but note that rental rates often go down as time goes on, and so if you bid and prepay for your car through one of these sites, you may end up overpaying if the AutoSlash rate drops below your prepaid rate. We generally advise not to bid for a rental car on one of these sites unless it's less than a few days before your pick-up date and the rate is much lower than the best rate that we can quote.
Other sites do allow you to change or cancel prepaid reservations, but there's usually a fee for doing so. This fee may increase the closer it is to your rental date and may even be nonrefundable in the last few days or week before your rental. Be sure you read the terms and conditions of your prepaid rate very carefully to make an educated decision as to whether it's worth prepaying. You'll want to be sure you've requested a quote for the best discounted rates we can find before booking a prepaid reservation elsewhere.
Also, click here to check out our more extensive article on prepaid reservations for much more information on this topic.