CarRentals.com, a unit of the Hotwire Group, introduced a free iPhone app, enabling users to search and book domestic and international car rentals without leaving the application.
In fact, CarRentals.com, which aggregates regional and high-profile car-rental brands, claims to offer "the first comprehensive car rental search and booking application for the the Apple iPhone."
Users can search car-rental locations via current location using the iPhone's GPS capabilities or can enter airport code, zip code or city.
CarRentals.com argues that users will save money on last-minute bookings if they reserve a car from the iPhone instead of being subjected to walk-in rates.
Hotwire acquired a controlling interest in CarRentals.com in 2008, and operates the unit as a separate brand.
CarRentals.com also has a mobile site.