"Just say no" to Collision Damage Waivers: Also known as Loss Damage Waivers, they'll add more than $9 a day to your rental cost, unless you sign the CDW agreement making you responsible for damage. Many, but not all, states have outlawed this liability by requiring car rental companies to pay for collision insurance. But even if your state allows it, you can avoid the hefty fees by using a credit card or bank card that covers collision.

Looking on the web

Breezenet bnm.com offers discounts (up to 20 percent) and savings at the major car companies, regional renters and selected "exotic" car rental agencies. Can search companies by airport location nationally and internationally. Has a section on "Last-Minute Specials" and also lists the deals available from several companies.

SideStep (sidestep.com) searches the major car companies, the online bookers, and several smaller agencies for the best rate. It runs along-side other search engines for easy rate comparison.

Low-cost auto rentals

Outside the mainstream car rental agencies such as Hertz, Avis, Budget, Enterprise, Alamo, and National, there are smaller, lesser-known companies that offer discounted automobile rentals. The upsides to renting with such a discounter is obvious: It'll cost less money. The downsides vary. Some use older or second-hand cars. Other agencies are very small, perhaps with a single location, and services will be far less extensive than the major players (which is important should anything go wrong). But if you're willing to take the slight risk with an older car or a smaller rental company, chances are you'll pay less than at a mainstream agency (but still look at the bigger companies too, to compare).

Here are some sources for low-cost auto rentals:

Rent-A-Wreck (800/944-7501, rentawreck.com) is the overly apologetic moniker for the company that used to discount just older cars through much of the U.S., but that now deals in luxury sedans as well as SUVs. Rest assured its automobiles are not "wrecks" by any means (not usually anyway), and its rates often come in well under Hertz, Avis, Alamo and the like. Be aware that some states have dozens of R-A-W branch locations, while others have one or none.

Car Rental Express (888/557-8188, carrentalexpress.com) is a web site that exclusively searches rates and availability for over 300 independent, locally owned car rental agencies in the United States, Canada, Europe and the Caribbean. Prices quoted on the site include all taxes and fees, and there are online coupons available for additional discounts. Daily rates are 25-30 percent less than the majors, and weekly rates are 15 percent cheaper. All agencies undergo a background check and Car Rental Express promises that 99 percent use new vehicles.

AutoEurope (888/223-5555, autoeurope.com) suffers none of the downsides listed above (it is a big operation and its cars are not old), yet it often undercuts the rates of worldwide operations like Hertz and Avis. It is a top option for short-term rentals all over Europe.

Renault Eurodrive (800/221-1052, renaultusa.com) is often a less expensive option for longer-term vacationers abroad, meaning people who are staying at least 17 days in Europe and who plan to take out a short-term lease. Compare with AutoEurope's rates.

Dan Dooley (800/331-9301, dan-dooley.ie) is a discount rental operation for Ireland only, although it has offices outside the Emerald Isle. It offers a wide array of cars models and sizes, and all of its quote rates are in Euros.