Probably not an original thought. A city car concept. Build a light weight car running on a series of ramps. Almost like a saw tooth. The car generates electricity as it coasts down. The stored electricity is used to lift the car up to the next ramp. Like they do on rides in Disney land. The small amount of additional energy required is generated with solar power and wind power. The ramps are clad with solar panels and the tall columns used to build the ramps carry the wind generators. We could have close to perpetual motion.  We could have ramps criss crossing a city and have 1, 2 & 4 person capsule car built in modular form. Maybe we ask for volunteers to get involved on a pilot plant for a forward thinking city