AutoSlash is a great site to save money on car rentals, offering you the best rates from all the main rental companies. Once we chose the deal we wanted, we were directed to Priceline to compete the booking. We could then track the reservation on the AutoSlash site and they sent notifications of better rates. You can just rebook and cancel the original booking. There were no cancellation charges (make sure the one you book states free cancellation). We had our car for over a month and were not charged until we returned the vehicle. The team at AutoSlash respond extremely quickly to any questions you may have. We have no hesitation in recommending them and will certainly be booking our rental cars through their site again.