A little prep will help you hold the line on nuisance charges and fees. June 1, 2010 By Thomas M. Anderson, Associate Editor Editor's Note: This story has been updated since its original publication. 1. Get ahead of the curve. Your goal is not to pay for insurance you already have. So before you hit the rental desk, find out what coverage your auto policy and credit-card benefits provide. First, call your insurer. Then call the toll-free number on the credit card you'll use to pay for the rental.2. Who covers what. Your auto policy generally covers rental-car damage. If, however, you've dropped comprehensive or collision coverage on your car, the rental car will not be covered if it is stolen or damaged in an accident. Your credit-card benefits supplement your auto coverage. Most cards will pick up your deductible, and premium cards offer beefier coverage. But credit-card protection doesn't include liability. 3. You may not need extra insurance. The clerk behind the desk will offer you a collision damage waiver (sometimes called a loss damage waiver), which can cost $10 to $20 per day. The CDW shields you if the rental car is damaged or stolen. But as long as the rental is for personal use and you have collision coverage, your own insurance will cover the rental (with the same deductibles that apply to your own car). Advertisement 4. But it could come in handy. Even if you have coverage through your auto insurance, you may want to take the CDW. It will help you avoid the hassle of your insurer's claims process and keep an accident off your record. Plus, car-rental agencies have been slapping customers with hefty "loss of use" and administrative fees. Most states do not include "loss of use" coverage in their standard auto policies; only Connecticut, Louisiana, Minnesota, New York, North Dakota, Rhode Island and Texas require such coverage. Caveat: By accepting the waiver from the rental-car company, you void the terms of your credit card's insurance benefits. 5. It gets complicated overseas. Generally, your auto insurance does not cover you when you rent a car abroad, although some policies may apply when you drive in Canada and Mexico (check with your insurer). Many credit-card companies withhold coverage in countries with lousy accident records. For example, American Express and MasterCard exclude Australia, Ireland, Israel, Italy, Jamaica and New Zealand. Of the countries on that list, Visa takes issue with Ireland, Israel and Jamaica. 6. Bring your own GPS. Rental-car companies will nickel-and-dime you for bonus equipment, such as GPS units, which can cost $12 per day, and child car seats, about $10 per day. Bring your own digital music player and connectors to use as an alternative to satellite radio ($3 per day). 7. Gas up on your own. If you are in a hurry, paying for a full tank of gas ahead of time will save you the hassle of filling up on the way to the airport. But if you plan ahead, you can locate cheaper gas than the rate quoted at the counter. Plus, unless you expect to run through a full tank on your trip, you might be paying for fuel you don't use. 8. Help move the fleet. You might get a seasonal deal if you drive a rental one way from Florida (because you're helping the company move equipment). In April, Alamo offered one-way rentals from Florida to any other state in the continental U.S. for as little as $10 per day.