A car is essential for San Diego's sprawling freeway system and comes in handy for touring Baja California (though the trolley serves the border at Tijuana). Rates in San Diego fluctuate with seasons and demand, but generally begin at $39 a day and $250 a week for an economy car with air-conditioning, automatic transmission, and unlimited mileage. This does not include tax on car rentals, which is 7.5%.
In California you must be 21 to rent a car, and rates may be higher if you're under 25. Some agencies will not rent to those under 25; check when you book. Children up to age six or 60 pounds must be placed in safety or booster seats. Non-U.S. residents must have a license whose text is in the Roman alphabet, though it need not be in English. An international license is recommended but not required.