Advantages and disadvantages of RFID and GPS?

we want to use any one of the above technologies for tracking the vehicles in our plant. Hence to select the best technology the above clarification is required. Our requirements is for tracking around 400 vehciles a day.
Answer: Microwave RFID tags are used in long range access control for vehicles.
Since the 1990's RFID tags have been used in car keys. Without the correct RFID, the car will not start.
In January 2003, Michelin began testing RFID transponders embedded into tires. After an 18 month testing period, the manufacturer will offer RFID-enabled tires to car makers. Their primary purpose is tire tracking in compliance with the United States Transportation, Recall, Enhancement, Accountability and Documentation Act (TREAD Act).
Starting with the 2004 model year, a Smart Key/Smart Start option became available to the Toyota Prius. Since then, Toyota has been introducing the feature on various models globally under both the Toyota and Lexus brands, including the Toyota Avalon (2005 model year), Toyota Camry (2007 model year), and the Lexus GS (2006 model year). The key uses an active RFID circuit allowing the car to detect the key approximately 3 feet from the sensor. The driver can open the doors and start the car with the key in a purse or pocket.

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Automobiles can be equipped with GPS receivers at the factory or as after-market equipment. Units often display moving maps and information about location, speed, direction, and nearby streets and landmarks.