Although you may certainly reserve a car anytime, It’s best to make your car rental reservations in advance. You will have more vehicle options available to you and will generally get a better price. Car rental pricing is based on availability. The more vehicles available, the lower the prices will generally be. There are some things as “last minute specials” but they are hard to find; you have to be at the right place at the right time. Advanced bookings allow the car rental companies to manage their fleet and adjust it accordingly.
An advanced booking will hold a vehicle for the location, dates and times that you have selected, at the price you agreed to at the time of booking.