some priceline car rental tips
A couple of helpful hints I've discovered recently.
If you book airfare with priceline (a good idea, because you can get a 3% rebate through fatwallet.com), priceline will allow you to add a car rental to the reservation at a certain price, which may look quite attractive. Don't do it! Try a separate bid for a couple dollars less. It's worked a couple times for me (just like when their hotel system lets you bid again for an extra few dollars).
Another trick is to REALLY low ball your car rental bid. Like if Hotwire is getting $25/day, type in an $8 bid. Priceline will usually tell you that your bid is silly, but that you'll have a "good chance" at $18. Try offering them $15. It's another good method of price discovery.