Rental rates vary depending on the size of the car, availability, and the rental agency.

Most rental firms offer several sizes of automobiles, ranging from compact through intermediate and full-sized. Moving up a size is generally not very expensive, but specialty cars and vans/trucks often cost much more.

Local supply and demand also has an enormous effect on rental rates. Leisure areas such as Florida are usually very inexpensive, since the major rental agencies compete with dozens of smaller firms. Cities such as New York and Chicago tend to be very expensive, since space is limited and demand is high.

There is also tremendous variation depending on the reservations made for that day. Rental firms are increasingly using yield management systems to predict demand and raise prices in popular areas. This means that rates are likely to go up if there is a major convention or new tourist attraction.

Depending on the rental agency you choose, rates may be as little as one-half of the most expensive choice. For one-time rentals, Hertz and Avis are generally at the top of the price scale, with Thrifty, Dollar, and Alamo nearer to the bottom. However, corporate discounts can result in 20%-25% savings off daily rental rates.