This is a 2002 model EVT 4000. They get 30 miles/hr max speed and with fresh batteries will do over 20 miles range. It's very well made and the EVT corporation has been around for a long time. 2002 was the first year they were imported to the U.S. They never sold it with this color combination, but Electric Motorsport had put this bike together as a demonstration unit and I liked the mix of colors as a way of being more visible. To me visibility equals safety.
This bike was modified by Todd Kollin, Electric Motorsport, to have a turbo mode. There is room behind the seat to stuff an 18 amp-hour battery and that, along with some special circuitry, allows the motor voltage to be switched to 60 volts on the fly. The bike is normally 48 volts with 4 50-amp-hour batteries under the seat.
With the turbo mode the controller remains at 48 volts and most of the time the motor sees 48 volts. Once you get up to speed, and realize you need more speed, there is a switch under your right thumb. Pressing the switch bypasses the controller sending 60 volts directly to the motor. It's just like the passing gear you might have on a gas car, and you can zoom up to perhaps 40 miles per hour.
Generally this bike is so extremely quiet, due to the hub motor (no chain noise) that it always felt like riding a magic flying carpet.