The Mach 6 is a never-before-seen version of the Mach 5 that was thought up by the Wachowski Brothers for the Speed Racer movie. It has a single-seat, driver-in-center architecture characteristic more of Indy or Formula I class vehicles than the open-stock or Chaparral style that inspired the Mach 5.
The Car can also be seen in Speed Racer: The Next Generation.