Here are contacts for selected car rental agencies:
Ace Rent a Car // 800-243-3443,
Advantage Rent-a-Car // 800-777-5500,
Alamo // 800-462-5266,
Auto Europe // 800-223-5555,
Avis // 800-331-1212; 800-331-1084 international,
Budget // 800-527-0700,
Dollar Rent a Car // 800-800-4000; 800-800-6000 international;
Enterprise Rent-a-Car // 800-325-8007,
Europcar // 877-940-6900,
Europe by Car // 800-223-1516,
Fox Rent a Car // 800-225-4369,
Hertz // 800-654-3131, 800-654-3001 international,
Kemwel International // 800-678-0678,
National // 800-328-4567, 800-227-3876 international,
Payless Car Rental // 800-729-5377,
Renault Eurodrive // 888-532-1221,
Rent-a-Wreck // 800-944-7501,
Thrifty // 800-847-4389,