You promised to return your rental car with a full tank of gas? Whatever you do, don't forget. Otherwise, you can expect to pay sky-high prices to have the rental agency do it for you.
See also: Foreign country car rentals.
A recent survey by USA Today found that agencies at 13 large U.S. airports were charging up to $9.29 per gallon.
Joan Rattner Heilman writes about good deals and where to find them.