The MX model has been redesigned into a full-size bike, and gets the full 54 horsepower version of the motor, along with much requested 18- and 21-inch wheels. Like all other Zeros, it also receives new battery packs for 2013, in this case either one or two plug-in 2.8 kWh modules. It is available with and will run on a single module, with the same low-end power and torque, but with the torque falling at higher rpm so that only half as much top-end power is produced. Plug in a second 42-pound pack, and power jumps to the full 54 horses while machine weight increases to 265 pounds. Extra packs are available, and can be swapped at the track in less than a minute.