The next time you make a car reservation, save yourself some dollars and use Autoslash. A friend of mine turned me on to this website and boom! — I saved over $50 on a three day rental from Enterprise. And it was easy!
All you do is make your rental car reservation like normal, and then enter the confirmation number and the rental company –Avis, Hertz, etc. Autoslash then begins their magic and searches for a lower price while you sit back and enjoy the savings. It emails you when it finds a lower price (it almost always does) and off you go to the rental counter, easy as that.
I’m not sure how they work, nor do I really care. All I know is that It works. Try it and let me know how it works for you.