If I have purchased a rental car but now it is listed at a cheaper rate, can I change my reservation to the new cheaper rental car? User's recommendation: Beware - I found a price of a car for over $100 less than I booked it. I email Auto Rentals and crickets. No response. Don't book too early as the price will go down and they will not honor it if you already booked a car, even if it is the same type of car at the same rental place.