The Mach Five as known as “Mach Go! Go! Go!” in Japan version this is the car was designed, built, and created by “Pops Racer” (Daisuke Mifune), Speed Racer’s father. It features a set of special devices which Speed Racer uses throughout the series.
In the original 1967 series, the Mach Five is a white racing car with an “M” written on its hood (which does not stand for “Mach 5”, but instead stands for “Mifune”, both Go’s last name, and the name of his father’s motor company). In the 1993 American remake, the design was completely changed.
Its name probably derives from the fact that speeds above Mach 5 are known as hypersonic. However, the Mach Five cannot reach Mach speeds. It was just a car.