sentences:  The PHEV Sprinter's engine could be turned off by the driver for operation in historic European city centers that had outlawed internal-combustion engines.By the end of the year, Dr. Frank's student teams had built and operated seven proof-of-concept and proof-of-demonstration prototype Plug-in Hybrid Electric Vehicles, including 6-passenger sedans (Taurus and Sable), Sport Utility Vehicles (Suburban, Explorer), two-seater sports car (GM EV1), and two ground-up 80 mpg sports cars, and the CalCars PRIUS+ prototype and EDrive Systems conversions were demonstrated.Additional DaimlerChrysler Mercedes-Benz Sprinter 15-passenger van PHEV prototypes were completed.