Mach number temperature generally decreases with increasing altitude between sea level and , the speed of sound also decreases. For example, the standard atmosphere model lapses temperature to at altitude, with a corresponding speed of sound (Mach1) of , 86.7% of the sea level value. While the terms "subsonic" and "supersonic", in the purest sense, refer to speeds below and above the local speed of sound respectively, aerodynamicists often use the same terms to talk about particular ranges of Mach values. This occurs because of the presence of a "transonic regime" around M = 1 where approximations of the Navier-Stokes equations used
Mach Five 345 horsepower, and cost between $75,000 and $125,000 each. The Petersen Automotive Museum in Los Angeles, California has a mid-engine prototype of the Mach Fives in its collection. The Mach Five appears in the live-action film adaptation "Speed Racer", directed by the Wachowski brothers, produced by Joel Silver, and released by Warner Bros. Pictures. The Mach Five is an actual vehicle and used in the major race of the film. Instead of being driven on pavement, it was hung from a crane and had its effects computer-generated. Along with the Mach Five, the movie features the "Mach 4" and the