Nissan is the latest car company to experiment with a subscription model.  The company is test-marketing a new service in which drivers can pay a fixed price per month, then swap cars as often as once a day to suit their needs.  Called Nissan Switch, the program is available in two tiers:  Select includes the Altima, Rogue, Pathfinder and Frontier for $699 per month. Premium goes for $899 a month and offers a choice among the Leaf Plus, Maxima, Murano, Armada,Titan and 370Z, with an option to add the mighty GT-R for an additional $100 per day, with a 7-consecutive-day limit.  The monthly fee includes the vehicle, delivery, cleaning, insurance, roadside assistance and routine maintenance. Vehicles will be the latest model year featuring well-equipped trim levels. Some include driver-assist technology, allowing shoppers to try innovative features like Nissan ProPILOT Assist.